Unit:
1: Integers
Exercise: 1 (Multiple Choice Questions and Answers 1–25)
In Questions 1 to 25,
there are four options, out of which
only one is correct. Write the correct one.
Question: 1
When the integers are arranged in descending
or ascending order, then find out which of the following integers always
remains in the middle of the arrangement.
a.
b.
c.
d.
Solution:
(a)
Ascending order:
Descending order:
Hence the integer “ ”in the middle of both the
arrangements remains the same.
Question: 2
By observing the number line (Fig. 1.2), state
which of the following statements is not true.
Fig. 1.2
a. B is greater than
b.
A is greater than
c.
B is greater than A
d.
B is smaller than
Solution
(c)
As we know that, if a number lies on the
right side to the other number, then the number is greater.
Here, B is greater than but smaller than and A is greater than but smaller than Also, B is smaller than A.
Question: 3
By observing the above number line (Fig. 1.2),
state which of the following statements is true.
a. B is
b.
A is
c.
B is
d.
B is
Solution
(d)
Since, B lies at the left side of ,
so it will be negative and it is at 4th place. So,
Similarly, A lies at the right side of ,
so it will be positive and it is at 7th place.
So, and the value of
Question: 4
Next three consecutive numbers in the pattern 11, 8, 5, 2, --, --, -- are
a.
b.
c.
d.
Solution
(d)
By observing the pattern, difference
between two consecutive numbers is ,
So, next number will be
Similarly, next two numbers are:
Question: 5
The next number in the pattern _______ is
a.
b.
c.
d.
Solution
(b)
By observing the series, the difference
between two consecutive numbers is , i.e.
So, next number will be .
Question: 6
Which of the following statements is not true?
a. When two positive integers are added, we always get a positive integer.
b. When two negative integers are added we always get a negative integer.
c. When a positive integer and a negative integer is added we always get a
negative integer.
d. Additive inverse of an integer is and additive inverse of is .
Solution
(c)
a.
True, when two positive
integers are added, the resultant number is also a positive integer.
b.
True, while adding integers, if
both the numbers have same sign, the resultant number also get that sign.
c.
False, while adding the
integers of different signs, the resultant number get the sign of greater
number.
d.
True, additive inverse of an
integer is the same integer value, with opposite sign.
Question: 7
On the following number line value ‘Zero’ is
shown by the point
a.
b.
c.
d.
Solution
(c)
All the points are equally spaced.
One division units
So,
Hence, zero is shown by the point
Question: 8
If ,, and
represent some integers on number line, then
descending order of these numbers is
a.
,
, ,
b.
, ,
,
c.
, , ,
d.
, ,
,
Solution
(c)
Descending order in number line, is from
right to left.
Accordingly,
comes first, comes second, comes third and
comes forth
Hence, descending order is , , ,
Question: 9
On the number line, the value of lies on right hand side of
a.
b.
c.
d.
Solution
(a)
equals to
Above, it is shown on
the number line that lies on the right
hand side of .
Question: 10
The value of does not lie between
a. and
b. and
c. and
d. and
Solution
(b)
equals to
On the number line, it is placed as
Now, as we see, lies between ( and ), ( and ) and ( and ). But it does not lie between and
Question: 11
Water level in a well was below the ground level. During
rainy season, rain water collected in different water tanks was drained into
the well and the water level rises above the previous level. The
wall of the well is high and a pulley is fixed at a
height of Raghu wants to draw water from
the well. The minimum length of the rope that he can use is
a.
b.
c.
d.
Solution
(a)
Details given in the question, can be
described in figure shown below
From the above figure, it is clear that minimum
length of the rope required to draw the water during the rainy season Distance between pulley and wall of well Height of the wall of the well Distance between water level during rainy
season and ground level
Question: 12
is not equal to
a.
b.
c.
d.
Solution
(c)
Ex: (As we know, in
multiplication, if sign of both numbers are different, then the sign of the
resultant is negative and if sign of both numbers are same, then the sign of
the resultant is positive.)
Option a.
Option b.
Option c.
Option d.
Question: 13
is equal to
a.
b.
c.
d.
Solution
(d)
Question: 14
Which of the
following is not the additive inverse of ?
a.
b.
c.
d.
Solution
(a)
Additive inverse of is [additive inverse of an
integer is the same integer value, with opposite sign] So,
Option a.
Option b.
Option c.
Option d.
Question: 15
Which of the following is the multiplicative
identity for an integer ?
a.
b.
c.
d.
Solution
(b)
Multiplicative identity for an integer a is
[a multiplicative identity is that identity in which any number is
multiplied by that identity, it gives out the same number.]
Question: 16
is not equal to
a.
b.
c.
d.
Solution
(d)
as
multiplication is commutative, i.e.,
(as
multiplication is associative, i.e.,
Hence, is not equal to
Question: 17
is not same as
a.
b.
c.
d.
Solution
(c)
Also,
[using
distributive property, i.e. ]
Hence, is not same as
Question: 18
is not same as
a.
b.
c.
d.
Solution
(c)
[using distributive property, i.e. ]
[as addition is
commutative, i.e. ]
Also,
Hence, is not same as
Question: 19
is equal to
a.
b.
c.
d.
Solution
(a)
(taking out as common)
Question: 20
is not same as
a.
b.
c.
d.
Solution
(a)
But division is not commutative, hence
Question: 21
Which of the following does not represent an
integer?
a.
b.
c.
d.
Solution
(d)
An integer is a whole number (not a
fractional number) that can be positive, negative or zero. So,
a.
b.
c.
d.
(not an integer)
Question: 22
Which of the following is different from the
others?
a.
b.
c.
d.
Solution
(c)
Option a.
Option b.
Option c.
Option d.
Question: 23
Which of the following shows the maximum rise in
temperature?
a.
to
b. to
c.
to
d.
to
Solution
(b)
Rise in temperature,
a.
b.
c.
d.
Question: 24
If and are two integers, then which of
the following may not be an integer?
a.
b.
c.
d.
Solution
(d)
Addition, subtraction and multiplication of
two or more integers is always an integer. But, division of integers may or may
not be an integer.
e.g. (not an integer)
(integer)
Question: 25
For a non-zero integer a, which of the following
is not defined?
a.
b.
c.
d.
Solution
(a)
Division of any number by zero is not
defined, not defined .
Encircle
the odd one of the following (Questions 26 to 30).
Question: 26
Encircle the odd one
of the following
a.
b.
c.
d.
Solution
(c)
Among all the options each pair of integers
give the same value ( ) of except the option (c). So, odd one is option c.
Question: 27
Encircle the odd one
of the following
a.
b.
c.
d.
Solution
(d)
By observation, we can say that the sum of
both values is same in options a, b and c. So, odd one is option d.
Question: 28
Encircle the odd one
of the following.
a.
b.
c.
d.
Solution
(c)
a.
b.
c.
d.
So, odd one is
option c.
Question: 29
Encircle the odd one
of the following
a.
b.
c.
d.
Solution
(d)
a.
b.
c.
d.
Here, option a, b and c are the negative
integers, but option d is not the negative integer. So, odd one is option d.
Question: 30
Encircle the odd one
of the following
a.
b.
c.
d.
Solution
(b)
a.
b.
c.
d.
Hence, value of options a, c, d, is same
but value of option b is different.
In
Questions 31 to 71, fill in the blanks to make the statements true.
Question: 31
Additive inverse of _______.
Solution
Additive inverse of a number is the
negative of that number.
As we know, addition is commutative for
integers, i.e.
Now, ‘ ’ is the additive
inverse of So, ‘a’ will be the answer.
Question: 32
_______
Solution
Division of by any number, result as zero. So, the answer
is
Question: 33
_______
Solution
[taking out as common]
Question: 34
Solution
[addition is associative for integers, i.e.
]
Question: 35
On the following number line, is represented by the point
_______.
Solution
On the number line, each division has equal
spacing of units.
So,
Hence, is represented by the point D.
Question: 36
If and are integers, then
Solution
Addition is associative for integers,
i.e.
Question: 37
Solution
Zero is an additive identity for
integers, i.e. for any integer
So,
Question: 38
Solution
Let be the missing number.
Then,
Hence,
Question: 39
Solution
We can write the equation as,
Question: 40
Solution
[In multiplication of integers, if both the
numbers have different signs, then the result is a negative number.]
Question: 41
Solution
[Multiplication is commutative, i.e. ]
Question: 42
While multiplying a
positive integer and a negative integer, we multiply them as _______ numbers
and put a _______ sign before the product.
Solution
When multiplying a positive integer and a
negative integer, we multiply them as whole numbers and put a negative
sign before the product.
Question: 43
If we multiply _______
number of negative integers, then the resulting integer is positive.
Solution
If we multiply even numbers of negative integers, then the resulting
integer is positive.
Question: 44
If we multiply six
negative integers and six positive integers, then the resulting integer is
_______.
Solution
If we multiply six negative integers and
six positive integers, then the resulting integer is positive. [Because
the product of even negative integers is a positive integer]
Question: 45
If we multiply five
positive integers and one negative integer, then the resulting integer is
_______.
Solution
If we multiply 5 positive integers and one
negative integer, then the resulting integer is negative.
Question: 46
_______ is the
multiplicative identity for integers.
Solution
is the multiplicative
identity for integers, i.e. for any integer .
Question: 47
We get additive
inverse of an integer when we multiply it
by _______.
Solution
Additive inverse of an integer is the same
integer value, with opposite sign. So, we get additive inverse of integer ,
when we multiply it by ‘ ’.
Question: 48
_______
Solution
Two negative integers make the resultant
integer, positive.
Question: 49
_______
Solution
Odd negative integers make the resultant
integer, negative.
Question: 50
_______
Solution
Two negative integers and one positive
integer make the resultant integer, positive.
Question: 51
Solution
Multiplication is associative for integers,
i.e.
So,
Question: 52
Solution
We can write the equation as,
[Integers show
distributive property of multiplication over addition, i.e. ]
Question: 53
_______
Solution
Question: 54
_______
Solution
Question: 55
Solution
Question: 56
_______
Solution
Question: 57
Solution
Question: 58
_______
Solution
Question: 59
When we divide a
negative integer by a positive integer, we divide them as whole numbers and put
a _______ sign before quotient.
Solution
When we divide a negative integer by a
positive integer or a positive integer by a negative integer, we divide them as
whole numbers and put a minus sign before quotient.
Question: 60
When is divided by _________ the quotient is .
Solution
When is divided by negative integer, i.e., the quotient is as both signs are cancelled out.
Question: 61
Division is the
inverse operation of _______
Solution
Division is the
inverse operation of multiplication.
Question: 62
_______
Solution
[division is inverse of multiplication]
Question: 63
_______
Solution
[division is inverse of multiplication]
Question: 64
_______
Solution
[division is inverse of multiplication]
Question: 65
_______
Solution
Question: 66
_______
Solution
Question: 67
Solution
Question: 68
Solution
Question: 69
Solution
Question: 70
_______
Solution
Question: 71
_______
Solution
In
Questions 72 to 108, state whether the statements are True or False.
Question: 72
is same as
Solution
True
Question: 73
is greater than
Solution
False
And
So, is greater than
Question: 74
Sum of two negative integers always gives a
number smaller than both the integers.
Solution
True
e.g. Taking two negative integers, i.e. and
and
Question: 75
Difference of two negative integers cannot
be a positive integer.
Solution
False
e.g. Taking two negative integers,
i.e. and
Question: 76
We can write a pair of integers whose sum
is not an integer.
Solution
False
Because, sum of two integers is always be
an integer.
Question: 77
Integers are closed under subtraction.
Solution
True
Because, if we subtract two integers, we
get another integer.
Question: 78
is same as
Solution
True
Because, addition is commutative, i.e.
Question: 79
When we change the order of integers, their
sum remains the same.
Solution
True
Because, sum of two integers is
commutative, i.e. for two integers and
Question: 80
When we change the order of integers their
difference remains the same.
Solution
False
Subtraction of two integers is not
commutative, i.e. for two integers and
Question: 81
Going towards east first and then back is same as going towards west first and then going back.
Solution
True
Case
I: Going towards East first, i.e. point A to C and then
back, i.e. C to B.
Case
2: Going towards West, i.e. A to D and then back, i.e. D to B.
As per the above figures, final position is
B, i.e., in East.
Question: 82
Solution
True
LHS and
RHS
Hence, LHS RHS
Question: 83
Solution
True
Product of two negative integers is a
positive integer, i.e. .
Question: 84
Solution
False
LHS
RHS
Hence,
Question: 85
Solution
False
LHS
RHS
Hence,
Question: 86
Solution
False
RHS
Hence,
Question: 87
Solution
True
LHS
RHS
Hence, LHS RHS
Question: 88
Product of two negative integers is a
negative integer.
Solution
False
Product of two negative integers is a
positive integer,
i.e. .
Question: 89
Product of three negative integers is a
negative integer.
Solution
True
Product of three negative integers is a
negative integer.
i.e. .
Question: 90
Product of a negative integer and a
positive integer is a positive integer.
Solution
False
Product of a negative integer and a
positive integer is a negative integer, i.e.
Question: 91
When we multiply two integers their product
is always greater than both the integers.
Solution
False
e.g. Let two integers be and
So,
and
Question: 92
Integers are closed under multiplication.
Solution
True
If we multiply two integers, we get an
integer.
e.g.
3 and 5 are integers and their product 15
is also an integer.
Also,
Where, 0 is also an integer.
So, integers are closed under
multiplication.
Question: 93
is same as .
Solution
True
When we multiply a number with we always get
= 0
Question: 94
Multiplication is not commutative for
integers.
Solution
False
Multiplication is commutative for integers,
i.e.
Where are integers.
Question: 95
is not a
multiplicative identity of integers.
Solution
True
is multiplicative
identity of integers, i.e. for any integer
Question: 96
can be written as
Solution
True
and
[using distributive property]
Question: 97
If are integers and then,
Solution
True
Multiplication can be distributive over
subtraction, i.e.
where a, b and c are integers.
Question: 98
Solution
False
Integers show distributive property of
multiplication over addition, i.e. ,
where and are integers.
Question: 99
Solution
True
Multiplication is commutative for integers,
i.e. where and are integers.
Question: 100
Solution
False
Division is not commutative for integers,
i.e. where and are integers.
Question: 101
Solution
False
Subtraction is not commutative for
integers, i.e. where and are integers.
Question: 102
Solution
True
Division of a negative integer and positive
integer is always a negative integer i.e., where and are integers.
Question: 103
Solution
True
[as division of a negative and positive
integer is always negative integer.]
Question: 104
Multiplication fact is same as division fact
Solution
True
Multiplication fact
|
Division fact
|
LHS
RHS
|
LHS
RHS
|
Question: 105
Integers are closed under division.
Solution
False
Because, when we divide two integers, we
may or may not get an integer. e.g. (integer) and (not an integer).
Question: 106
Solution
False
LHS
And RHS
Hence,
Question: 107
The sum of an integer and its additive
inverse is zero
Solution
True
Additive inverse is the number that when
added to a given number yields zero.
Question: 108
The successor of is
Solution
False
We know that, successor means adding to the given number.
Here, given number is [On multiplying by to any number the result is zero]
Hence, the successor of but
Question: 109
Observe the following patterns and fill in
the blanks to make the statements true:
a.
b.
Solution
a.
b.
Question: 110
Science Application: An atom consists of
charged particles called electrons and protons. Each proton has a charge of and each electron has a charge of Remember number of electrons is equal to
number of protons, while answering these questions:
a.
What is the charge on an atom?
b.
What will be the charge on an
atom if it loses an electron?
c. What will be the charge on an atom if it gains an electron?
Solution
a.
Let ‘a’ be the number of
electrons in an atom.
Number of
protons in the atom, will also be equal to a. Since, an atom has equal number
of protons and electrons.
Charge on one electron
Total charge in a electrons
Charge on one proton
Total charge in a protons
Hence, total
charge on the atom
Charge of electrons Charge of protons
b.
If an atom loses an electron,
it will have electrons and a protons.
Charge in one electron
Charge in electrons
Charge in one proton
Charge in a
protons
Hence, total
charge on the atom Charge of electrons Charge of protons
c.
If an atom gains an electron,
it will have electrons and a protons
Charge in one electron
Charge in electrons
Charge in one proton
Charge in a
protons
Hence, total
charge on the atom Charge of electrons Charge of protons
Question: 111
An atom changes to a charged particle
called ion if it loses or gains electrons. The charge on an ion is the charge
on electrons plus charge on protons. Now, write the missing information in the
table given below:
Name
of Ion
|
Proton
Charge
|
Electron
Charge
|
Ion
Charge
|
Hydroxide
ion
|
|
—
|
|
Sodium
ion
|
|
—
|
|
Aluminium
ion
|
|
|
—
|
Oxide
ion
|
|
|
—
|
Solution
a.
For Hydroxide ion,
Proton charge Electron charge lon charge
Electron charge lon charge – Proton charge
Electron charge
Hence, the
electron charge in a Hydroxide ion is
b.
For Sodium ion,
Electron charge lon charge — Proton charge
Hence, the
electron charge in a Sodium ion is
c.
For Aluminium ion,
lon charge Proton charge Electron charge
lon charge
Hence, the ion
charge in an Aluminium ion is
d.
For Oxide ion,
lon charge Proton charge Electron charge lon charge
Hence, the ion
charge in an Oxide ion is
Question: 112
Social
Studies Application: Remembering that came immediately after ,
while solving these problems take as and as
a.
The Greeco-Roman era, when
Greece and Rome ruled Egypt started in the year and ended in the year .
How long did this era last?
b.
Bhaskaracharya was born in the
year and died in the year What was his age when he died?
c.
Turks ruled Egypt in the year and Queen Nefertis ruled Egypt about years before the Turks ruled. In what year did
she rule?
d.
Greek mathematician Archimedes
lived between and and Aristotle lived between and Who lived during an earlier period?
Solution
a.
The era lasted for
b.
Bhaskaracharya's age when he
died was years.
c.
Queen Nefertis ruled Egypt in
the year
d.
Aristotle lived earlier as comes before .
Question: 113
The table shows the lowest recorded
temperatures for each continent. Write the continents in order from the lowest
recorded temperature to the highest recorded temperature.
The Lowest Recorded
Temperatures
|
Continent
|
Temperature
(in Fahrenheit)
|
Africa
|
|
Antarctica
|
|
Asia
|
|
Australia
|
|
Europe
|
|
North America
|
|
South America
|
|
Solution
Lowest to heights (ascending order) in a
negative number, the number that has greater value of actually smaller and
vice-versa. So, accordingly, we arrange them in ascending order as i.e.
Antarctica Asia North America Europe
South America Africa Australia.
Question: 114
Write a pair of integers whose product is and there lies seven integers between them
(excluding the given integers).
Solution
For a pair of integers, whose product is and there lies seven integers between them
excluding given integers, only two solutions are possible, i.e. and and and .
1st Pair: Let 1st
integer & 2nd integer
& integers are lying between them.
2nd Pair: Let 1st
integer & 2nd integer
& integers are lying between them.
Question: 115
From given integers in Column I match an
integer of Column II so that their product lies between and :
Column I
|
Column II
|
|
|
|
|
|
|
|
|
Solution
which lies between and
which lies between and
which lies between and
which lies between and
Question: 116
Write a pair of integers whose product is and whose difference is
Solution
For a pair of integers, whose product is and whose difference is ,
one possible solution is
So, first integer and second integer
Their product and the difference between these two integers
is
Question: 117
Match the following
Column I
|
Column II
|
a.
|
i. Additive inverse of
|
b.
|
ii.
Additive identity
|
c.
|
iii.
Multiplicative identity
|
d.
|
iv.
|
e.
|
v.
|
f.
|
vi.
|
g.
|
vii.
|
h.
|
viii.
|
i.
|
ix.
|
Solution
a. vi.
b. iii.
is multiplicative identity
c. v. Both sign are cancelled
with each other
d. vii.
e. Viii. Any value which is
multiplied by becomes
f.
iv.
g. ii.
is an additive identity
h. ix
i.
i.
is additive inverse of
Question: 118
You have in your savings account at the beginning of
the month. The record below shows all of your transactions during the month.
How much money is in your account after these transactions?
Cheque No.
|
Date
|
Transaction Description
|
Payment
|
Deposit
|
|
|
Jal
Board Deposit
|
|
|
|
|
LIC
India Deposit
|
|
|
Solution
According to the question, Already
available amount
On with cheque number withdraw
Also, with cheque number on deposited amount was
In the same way, on with cheque number paid to LIC of India, also.
On with cheque number ,
deposited amount was
Thus, net amount available in bank account
will be Already saved amount Deposited amount Debited amount (paid amount)
Question: 119
a.
Write a positive integer and a
negative integer whose sum is a negative integer.
b.
Write a positive integer and a
negative integer whose sum is a positive integer.
c.
Write a positive integer and a
negative integer whose difference is a negative integer.
d.
Write a positive integer and a
negative integer whose difference is a positive integer.
e.
Write two integers which are smaller
than but their difference is
f.
Write two integers which are
greater than but their sum is smaller than
g.
Write two integers which are
greater than but their difference is smaller than
h.
Write two integers which are
smaller than but their difference is greater than
i.
Write two negative integers whose difference is
j. Write two integers such that
one is smaller than and other is greater than but their difference is
k.
Write two integers whose
product is smaller than both the integers.
l.
Write two integers whose product is greater than both the integers.
Solution
a.
A number of solutions can be
possible. e.g.
Let first
integer and second integer
Sum [negative integer]
b.
A number of solutions can be
possible.
e.g. Let first integer
and second integer
Sum [positive integer]
c.
A number of solutions can be
possible.
e.g. Let first
integer and second integer
Difference [negative integer]
d.
A number of solutions can be
possible.
e.g. Let first
integer and second integer
Difference
e.
For two integers, which are
smaller than but their difference is
Let first
integer and second integer and
Difference
f.
For two integers which are
greater than but their sum is smaller than Let first integer and second integer and
Sum
g.
For two integers which are
greater than but their difference is smaller than
Let first
integer and second integer and
Difference
h.
For two integers which are
smaller than but their difference is greater than
e.g. Let first
integer and second integer and
Difference
i.
A number of solutions can be possible.
e.g. Let first
integer and second integer
Difference
j. For two integers, such that
one is smaller than and other is greater than .
Let first
integer and second integer and
Difference
k.
A number of solutions can be
possible.
e.g. Let first
integer and second integer
Product and
l.
A number of solutions can be possible. e.g.
Let first
integer and second integer
Product and
Question: 120
What’s
the Error? Ramu evaluated the expression and came up with the answer What did Ramu do wrong?
Solution
Ramu went wrong in solving and took it as only.
Correct answer
Question: 121
What’s
the Error? Reeta evaluated for and gave an answer of What might Reeta have done wrong?
Solution
Reeta went wrong in solving and took it as
Correct answer
Question: 122
The table given below shows the elevations
relative to sea level of four locations.
Taking sea level as zero, answer the
following questions:
Location
|
Elevation (in m)
|
A
|
|
B
|
|
C
|
|
D
|
|
a.
Which location is closest to
sea level?
b.
Which location is farthest from
sea level?
c.
Arrange the locations from the
least to the greatest elevation.
Solution
a.
From the adjacent figure, we
can clearly see that C is closest to sea level.
b.
D is a farthest from sea level.
c.
Location from the least to the
greatest elevation will be in the order A, C, B and D.
Question: 123
You are at an elevation above sea level as you start a motor ride.
During the ride, your elevation changes by the following metres: What is your elevation relative to the sea
level at the end of the ride?
Solution
As per the given information, initial
position of motor was
During the ride, changes in elevation was Net change in
position Initial
position was So, at the end of the
ride the position would be
Question: 124
Evaluate the following, using distributive
property.
a.
b.
c.
d.
Solution
a.
Now, using
distributive property
b.
Taking out as common
c.
Taking out as common
d.
Taking out as common
Question: 125
If is an operation such that for integers and we have
then find
a.
b.
Solution
a.
We have,
Now, put and
b.
Now, put and
Question: 126
If is an operation such that for integers and we have then find
a.
b.
Also show that and
Solution
i. We have,
Now, put
Now, put
Clearly,
- Now,
put
Now, put
Clearly,
Question: 127
Below and represent different integers, where and By using following equations, find each of the
values:
a.
b.
c.
Explain your reasoning using the properties
of integers.
Solution
We have three
equations
(i)
(ii)
(iii)
And
a. By putting the value of in Eq. (i), we get
b.
From Eq. (ii),
But,
Hence, (ii) is possible, when
c. From Eq. (iii),
Put we get
Question: 128
Height of a place A is above sea level. Another place B is below sea level. What is the difference
between the levels of these two places?
Solution
As per the given information, we can draw
the diagram,
Let O be the point of level of sea.
Difference between
these two point, A
and B
Height between sea level and point A Height between point B and sea level
Question: 129
The given table shows the freezing points
in of different gases at sea level. Convert each
of these into to the nearest integral value using the
relation and complete the table,
Gas
|
Freezing Point at Sea
Level ( )
|
Freezing Point at Sea
Level ( )
|
Hydrogen
|
|
|
Krypton
|
|
|
Oxygen
|
|
|
Helium
|
|
|
Argon
|
|
|
Solution
For Hydrogen put
For Krypton put
For Oxygen put
For Helium put
For Argon put
Question: 130
Sana and Fatima participated in an apple
race. The race was conducted in parts. In the first part, Sana won by seconds. In the second part she lost by minute, then won by seconds in the third part and lost by seconds in the fourth part, she lost by seconds in the fifth part and won by seconds in the last part. Who won the race
finally?
Solution
Let difference in time denoted by positive,
when Sana wins the race and negative, when Sana loses the race.
Total difference in time taken by Sana in
all the six parts
Hence, Fatima won the race by
Question: 131
A green grocer had a profit of on Monday, a loss of on Tuesday and loss of on Wednesday. Find his net profit or loss in days.
Solution
As per the given information,
Profit on Monday and
loss on Tuesday and loss on Wednesday
Net profit Total profit Total loss
Now, total profit and total loss
Net profit
Question: 132
In a test, marks are given for every correct answer and mark are given for every incorrect answer.
Sona attempted all the questions and scored marks though she got correct answers.
a.
How many incorrect answers has
she attempted?
b.
How many questions were given
in the test?
Solution
Let be the correct answers and be the incorrect answers, given by Sona. It is
given that, if she gives correct answers and her score is
Since, for every correct answer, is given and for every incorrect answer, is given.
Hence,
a.
Total score
i.e.
i.e.
Hence
b.
Total number of questions correct answer incorrect answer
Question: 133
In a true-false test containing questions, a student is to be awarded marks for every correct answer and for every incorrect answer and for not supplying any answer. If Yash secured marks in a test, what are the possibilities of
his marking correct or wrong answer?
Solution
Since, Yash scored marks.
So, Minimum correct answers
Hence, there are two possibilities:
a.
correct answers and unattempted.
b.
correct answers, unattempt and wrong answer
Question: 134
A multistorey building has floors above the ground level each of height .
It also has floors in the basement each of height A lift in building moves at a rate of If a man starts from above the ground, how long will it take him to
reach at floor of basement?
Solution
Man covers the distance above the ground and man covers the distance below the ground
total distance
speed of the lift
Hence, time taken to reach second floor of
the basement
Question: 135
Taking today as zero on the number line, if
the day before yesterday is January, what is the date days after tomorrow?
Solution
If we take today as zero, then two days
before today is January.
Hence, days after tomorrow will be at place from zero on the number line.
So, required date will be January
January
Question: 136
The highest point measured above sea level
is the summit of Mt. Everest which is above sea level and the lowest point is
challenger Deep at the bottom of Mariana Trench which is below sea level. What is the vertical distance
between these two points?
Solution
As per the given information, we can draw
the diagram,
Let A be the point above the sea level and
B be the point below the sea level.
Vertical distance between points A and B Distance between point A and sea level Distance between point B and sea level