Questions · Page 4 of 5

1 Marks Question

Question 1511 Mark
Identify the Quantifiers in the following statement:
There exists a real number $x$ such that $x^2 + 1 = 0.$
Answer
Quantifier are the phrases like ‘There exists’ and ‘For every1, ‘For all’ etc.
There exists.
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Question 1521 Mark
Which of the following sentences are statements? Justify.Sum of opposite angles of a cyclic quadrilateral is 180°
Answer
We know that is either true or false but not both simultaneously.
It is true. Hence, it is a statement.
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Question 1531 Mark
Check the validity of the following statements:
r: 60 is a multiple of 3 or 5.
Answer
The statement is:
r: 60 ism ultiple of 3 or 5
is a com pound statement of the following statements:
p: 60 is multiple of 3
q: 60 is multiple of 5
Suppose q is false. That is, 60 is not a multiple of 5. Clearly p is true.
Thus, if we assume that q is false, then p is true.
Hence, the statement is true i.e. the statement "r" is a valid statement.
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Question 1541 Mark
Find out the following sentences are statements and which are not. Justify your answer.
Two non-empty sets have always a non-empty intersection.
Answer
It is a false assertive sentence. Two non-empty sets with no common elements can have an empty intersection. Therefore, it is a statement.
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Question 1551 Mark
All birds sing.
Answer
Negation of the given statement:
Some birds do not sing.
Or
There exists a bird that does not sing.
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Question 1561 Mark
For the following statements, determine whether an inclusive "OR" or exclusive "OR" is used. Give reasons for your answer.
Students can take Hindi or Sanskrit as their third language.
Answer
Exclusive OR is used because students can opt for either Hindi or Sanskrit as their third language.
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Question 1571 Mark
Write down the converse of following statement:
If all three angles of a triangle are equal, then the triangle is equilateral.
Answer
If the triangle is equilateral, then all three angles of the triangle are equal.
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Question 1591 Mark
Find out the following sentences are statements and which are not. Justify your answer.
The cat pussy is black.
Answer
It is a declarative sentence, which may be true or false but cannot be both at the same time, so it is a statement.
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Question 1601 Mark
Rewrite the following statements in the form of conditional statement:
The unit digit of an integer is 0 or 5 if it is divisible by 5.
Answer
p is sufficient for q ⇒ If an integer is divisible by 5, then its unit digits are 0 or 5.
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Question 1611 Mark
Find out the following sentences are statements and which are not. Justify your answer.
This sentence is a statement.
Answer
Without knowing the sentence, we cannot decide whether it is true or false. So, it is not a statement.
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Question 1621 Mark
Find out the following sentences are statements and which are not. Justify your answer.
Every rhombus is a square.
Answer
It is not true that every rhombus is a square because some rhombi may have all angles other than 90. So, it is a false statement.
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Question 1631 Mark
Write down the converse of following statement:
If S is a cyclic quadrilateral, then the opposite angles of S are supplementary.
Answer
If the opposite angles of a quadrilateral are supplementary, then S is cyclic.
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Question 1641 Mark
Which of the following statements are true and which are false? In each case give a valid reason for saying so:
r: Circle is a particular case of an ellipse.
Answer
True. Because a circle is an ellipse that has equal axes.
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Question 1651 Mark
Find out the following sentences are statements and which are not. Justify your answer.
The real number x is less than 2.
Answer
We cannot decide whether this sentence is true or false without knowing the value of x. So, it is not a statement.
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Question 1661 Mark
Determine the contrapositive of the following statements:
If she works, she will earn money.
Answer
If she does not earn money, then she will not work.
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Question 1671 Mark
Write down the converse of following statement:
If you go to Agra, then you must visit Taj Mahal.
Answer
If you must visit Taj Mahal, then you go to Agra.
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Question 1681 Mark
Rewrite the following statements in the form of conditional statement:
The square of an odd number is odd.
Answer
If p, then q ⇒ If the number is odd, then its square is odd number.
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Question 1691 Mark
Write down the negation of following compound statement:
6 is divisible by 2 and 3.
Answer
Let p: 6 is divisible by 2.
q: 6 is divisible by 3.
Then, the negation of the given compound statement is:
~(p ∧ q): 6 is not divisible by 2 or it is not divisible by 3
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Question 1701 Mark
Write down the negation of following compound statement:
All prime integers are either even or odd.
Answer
Let p: All prime integers are even.
q: All prime integers are odd.
Then, the negation of the given compound statement is given by ~ (p v q):
All prime integers are not even and all prime integers are not odd.
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Question 1711 Mark
Write the following statements in the form "if p, then q".
There is traffic jam whenever it rains.
Answer
If it rains, then there is a traffic jam.
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Question 1721 Mark
Write the following statements in the form "if p, then q".
It is necessary to have a passport to log on to the server.
Answer
It is necessary to have a passport to log on to the server.
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Question 1731 Mark
Write the component statements of the following compound statements and check whether the compound statement is true or false:
$x = 2$ and $x = 3$ are the roots or the equation $3x^2 − x − 10 = 0.$
Answer
The component statements of the given compound statement are:
  1. $x = 2$ is the root or the equation $3x^2 - x - 10 = 0.$
  2. $x = 3$ is the root or the equation $3x^2 - x - 10 = 0.$
The connective used is "and". So, both component statements must be true for the compound statement to be true. The statement $"x = 3x = 3$ is the root or the equation $3x^2 - x - 10 = 0"$ is false. Therefore, the compound statement is false.
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Question 1741 Mark
Which of the following sentences are statements? Justify.Sky is red.
Answer
We know that is either true or false but not both simultaneously.
It is false. Hence, it is a statement.
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Question 1751 Mark
Write the following statements in the form "if p, then q".
You can access the website only if you pay a subscription fee.
Answer
If you pay a subscription fee, then you can access the website.
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Question 1761 Mark
Negate the following statements:
There exists a number which is equal to its square.
Answer
Negation of the given statement:
There exists a number which is not equal to its square.
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Question 1771 Mark
For the following statements, determine whether an inclusive "OR" or exclusive "OR" is used. Give reasons for your answer.
To apply for a driving licence, you should have a ration card or a passport.
Answer
Inclusive OR because a person could have both ration card as well as passport.
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Question 1781 Mark
Identify the Quantifiers in the following statement:
There exists a statement in above statements which is not true.
Answer
Quantifier are the phrases like ‘There exists’ and ‘For every1, ‘For all’ etc.
There exists.
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Question 1791 Mark
Write the negation of the following simple statement:
Every real number is an irrational number.
Answer
Every real number is not an irrational number.
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MCQ 1801 Mark
Which of the following cannot be the negation of the statement “Everyone in India speaks Hindi”?
  • A
    Not everyone in India speaks Hindi.
  • No person in India speaks Hindi.
  • C
    Someone in India does not speaks Hindi.
  • D
    At least one person in India who does not speaks Hindi.
Answer
Correct option: B.
No person in India speaks Hindi.
Negation of everyone is not everyone. So, negation of the given statement should be “Not everyone in India speaks Hindi”, “Someone in India does not speaks Hindi”, “At least one person in India who does not speaks Hindi”. “No person in India speaks Hindi” cannot be the negation of the given statement as this means no one speaks Hindi which does not means not everyone.
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Question 1811 Mark
Find the component statements of the following compound statements.
A rectangle is a quadrilateral or a 5-sided polygon.
Answer
p: A rectangle is a quadrilateral.
q: A rectangle is a 5-sides polygon.
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Question 1821 Mark
Find the component statements of the following compound statements.
plants use sunlight, water and carbon-dioxide for photosynthesis.
Answer
p: Plants use sunlight for photosynthesis.
q: Plants use water for photosynthesis.
r: Plants use carbon-dioxide for photosynthesis.
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Question 1831 Mark
Write the negation of the following simple statement:
The number 17 is prime.
Answer
The number 17 is not prime.
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Question 1841 Mark
Translate the following statement into symbolic form:
Either x or x + 1 is an odd integer.
Answer
p: x is an odd integer.
q: (x + 1) is an odd integer.
p v q: Either x or (x + 1) is an odd integer.
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Question 1851 Mark
Write the following statements in the form "if p, then q".
It rains only if it is cold.
Answer
If it rains, then it is cold.
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Question 1861 Mark
Translate the following statement into symbolic form:
Students can take Hindi or English as an optional paper.
Answer
p: Students can take Hindi as an optional paper.
q: Students can take English as an optional paper.
p v q: Students can take Hindi or English as an optional paper.
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Question 1871 Mark
Show that the statement:
$p: "$If x is a real number such that $x^3 + x = 0, $ then $x$ is $0"$ is true by.
Method of contrapositive
Answer
Let $q$ and $r$ be the statements given
$q: x$ is a real number such that $x^3 + x = 0.$
$r: x$ is $0.$
Then, $p:$ if $q$, then $r.$
Method of contrapositive: Let $r$ be not true. Then,
$r$ is not true.
$\Rightarrow\text{x}\not=0,\ \text{x}\in\text{R}$
$\Rightarrow\text{x}(\text{x}^2+1)\not=0,\ \text{x}\in\text{R}$
$\Rightarrow q$ is not true
Thus, $-r = -q.$
Hence, $p : q \Rightarrow r$ is true.
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Question 1881 Mark
Write the component statements of the following compound statements and check whether the compound statement is true or false:
To enter into a public library children need an identity card from the school or a letter from the school authorities.
Answer
The component statements of the given compound statement are:
  1. To enter into a public library, children need an identity card from the school.
  2. To enter into a public library, children need a letter from the school authorities.
The compound statement is true because both component statements are true.
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Question 1891 Mark
Rewrite the following statements in the form "p if and only if q".
q: If a quadrilateral is equiangular, then it is a rectangle and if a quadrilateral is a rectangle, then it is equiangular.
Answer
A quadrilateral is a rectangle if and only if it is equiangular.
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Question 1901 Mark
Write down the negation of following compound statement:
|x| is equal to either x or -x.
Answer
Let p:|x| is equal to x.
q:|x| is equal to -x.
Then, the negation of the given compound statement is:
~(p v q): |x| is not equal to JC and it is not equal to -x.
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Question 1911 Mark
Write down the converse of following statement:
If the sum of squares of two sides of a triangle is equal to the square of third side of a triangle, then the triangle is right angled.
Answer
If the triangle is right triangle, then the sum of the squares of two sides of a triangle is equal to the square of third side.
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Question 1921 Mark
Write down the negation of following compound statement:
All rational numbers are real and complex.
Answer
Let p: All rational numbers are real.
q: All rational numbers are complex.
~p: All rational numbers are not real.
~q; All rational numbers are not complex.
Then, the negation of the given compound statement is:
~(p ∧ q): All rational numbers are not real or not complex.
[~(p ∧ q) = ~p v ~ q]
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Question 1931 Mark
Determine the contrapositive of the following statements:
If it snows, then they do not drive the car.
Answer
If they do not drive the car, then there is no snow.
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Question 1941 Mark
Write down the contrapositive of the following statement:
If n is a natural number, then n is an integer.
Answer
If n is not an integer, then it is not a natural number.
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Question 1951 Mark
Check the validity of the following statements:
q: 125 is a multiple of 5 and 7.
Answer
The statement is:
"125 is multiple of 5 and 7"
Since 125 is a multiple of 5 but it is not a multiple of 7. So, q is not a true statement i.e. the statement "q" is not a valid statement.
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Question 1961 Mark
Write down the contrapositive of the following statement:
If x is a real number such that 0 < x < 1, then x 2 < 1.
Answer
If x 2 > 1 then x is not a real number such that 0 < x < 1.
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Question 1971 Mark
Write the negation of the following statements:
The sun is cold.
Answer
Negation of the given statement:
The sun is not cold.
Or
It is not true that the sun is cold.
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Question 1981 Mark
Which of the following statements are true and which are false? In each case give a valid reason for saying so:
q: The centre of a circle bisects each chord of the circle.
Answer
False. Because, a chord does not have to pass through the centre.
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Question 1991 Mark
Write down the converse of following statement:
If two triangles are similar, then the ratio of their corresponding sides are equal.
Answer
If the ratio of corresponding sides of two triangles are equal, then triangles are similar.
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Question 2001 Mark
Are the following pairs of statements are negation of each other:
The number x is not a rational number.
The number x is not an irrational number.
Answer
The given statement in this pair are the negation of each other.
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1 Marks Question - Page 4 - MATHS STD 11 Science Questions - Vidyadip