Questions · Page 3 of 5

1 Marks Question

Question 1011 Mark
Find out the following sentences are statements and which are not. Justify your answer.
There are 35 days in a month.
Answer
It is a false assertive sentence, so it is a false statement.
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Question 1021 Mark
Check whether the following pair of statements are negation of each other. Give reasons for your answer.
  1. $a + b = b + a$ is true for every real number $a$ and $b.$
  2. There exist real numbers a and b for which $a + b = b + a.$
Answer
the negation of ​the statements
$a + b = b + a$ is true for every real number $a$ and $b.$
is:
There exist real numbers $a$ and $b$ for which $a + b \neq b + a.$
So, the given statment is of not tha negation of the first statment.
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Question 1031 Mark
Which of the following sentences are statements? Justify.15 + 8 > 23
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 1041 Mark
Rewrite the following statements in the form "p if and only if q".
r: For you to get an A grade, it is necessary and sufficient that you do all the homework regularly.
Answer
You get an A grade if and only if you do all the homework regularly.
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Question 1051 Mark
Write the negation of the following simple statement:
$\sqrt{5}$ is a rational number.
Answer
$\sqrt{5}$ is not a rational number.
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Question 1061 Mark
Which of the following statements are true and which are false? In each case give a valid reason for saying so:
$\text{t}:\sqrt{11}$ is a rational number.
Answer
False. Because square roots of prime num bars are irrational num bars.
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Question 1071 Mark
Write the component statements of the following compound statements and check whether the compound statement is true or false:
All rational numbers are real and all real numbers are not complex.
Answer
The component statements of the given compound statement are:
  1. All rational numbers are real.
  2. All real numbers are not complex.
The compound statement is false because all real numbers are complex. The connective used is "and". So, even if one component statement is false, the compound statement is false.
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Question 1081 Mark
Write the negation of the following statements:Ravish is honest.
Answer
Negation of the given statement:
It is not true that Ravish is honest.
Or
Ravish is not honest
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Question 1091 Mark
Rewrite the following statements in the form of conditional statement:
You will fail, if you will not study.
Answer
p only if q ⇒ If you do not study, then you will fail.
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Question 1101 Mark
Write the negation of the following statements:
Banglore is the capital of Karnataka.
Answer
Negation of the given statement:
It is not true that Bangalore is the capital of Karnataka.
Or
Bangalore is not the capital of Karnataka.
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Question 1111 Mark
Both the diagonals of a rectangle have the same length.
Answer
Negation of the given statement:
Both the diagonals of a rectangle do not have the same length.
Or
Both the diagonals of a rectangle have different lengths.
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Question 1121 Mark
Write down the converse of following statement:
If x is zero, then x is neither positive nor negative.
Answer
If x is nether positive nor negative then x = 0.
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Question 1131 Mark
Identify the Quantifiers in the following statement:For every natural number x, x + 1 is also a natural number.
Answer
Quantifier are the phrases like ‘There exists’ and ‘For every1, ‘For all’ etc.
For every.
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Question 1141 Mark
Write the negation of the following simple statement:
All similar triangles are congruent.
Answer
There exist similar triangles which are not congruent.
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Question 1151 Mark
Write down the contrapositive of the following statement:
If x and y are negative integers, then xy is positive.
Answer
If xy is not positive integer, then x or y is not negative integer.
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Question 1161 Mark
Write the component statements of the following compound statements and check whether the compound statement is true or false:
The sand heats up quickly in the sun and does not cool down fast at night.
Answer
The component statements of the given compound statement are:
  1. The sand heats up quickly in the sun.
  2. Sand does not cool down fast at night.
The compound statement uses "and" as the connective. For the compound statement to be true, both the component statements must be true. The second component statement "Sand does not cool down fast at night" is false. Sand cools down fast at night. Therefore, the compound statement is false.
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Question 1171 Mark
Write down the converse of following statement:
If today is Monday, then tomorrow is Tuesday.
Answer
If tomorrow is Tuesday, then today is Monday.
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Question 1181 Mark
Determine whether the argument used to check the validity of the following statement is correct:
p: "If $x^2$ is irrational, then $x$ is rational"
The statement is true because the number $\text{x}^2=\pi^2$ is irrational, therefore $\text{x}=\pi$ is irrational.
Answer
The argument used to check the validity of the given statement is not correct because it does not produce a contradiction.
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Question 1191 Mark
State the converse and contrapositive of the following statements:
If you live in Delhi, then you have winter clothes.
Answer
Converse:
If you have winter clothes, then you live in Delhi.
Contrapositive:
​If you do not have winter clothes, then you do not live in Delhi.
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Question 1201 Mark
Rewrite the following statements in the form of conditional statement:
The square of a prime number is not prime.
Answer
q is necessary for p ⇒ If any number is prime, then its square is not prime.
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Question 1211 Mark
Which of the following statements are true and which are false? In each case give a valid reason for saying so:
p: Each radius of a circle is a chord of the circle.
Answer
False. Because, no radius of a circle is its chord.
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Question 1221 Mark
Find the component statements of the following compound statements:
The sky is blue and the grass is green.
Answer
The component statements of the given compound statement are:
The sky is blue.
The grass is green.
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Question 1231 Mark
Negate the following statements:
All the students completed their homework.
Answer
Negation of the given statement:
Some students did not complete their homework.
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Question 1241 Mark
Find out the following sentences are statements and which are not. Justify your answer.
Are all circles round?
Answer
It is an interrogative sentence, so it is not a statement.
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Question 1251 Mark
Write the following statements in the form "if p, then q".
It never rains when it is cold.
Answer
If it is cold, then it never rains.
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Question 1261 Mark
Write down the converse of following statement:
If x : y = 3 : 2, then 2x = 3y.
Answer
If 2x = 3y then x : y = 3 : 2.
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Question 1271 Mark
Find the component statements of the following compound statements.
0 is less than every positive integer and every negative integer.
Answer
p: 0 is less than every positive integer.
q: 0 is less than every negative integer.
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Question 1281 Mark
Which of the following sentences are statements? Justify.y + 9 =7
Answer
We know that is either true or false but not both simultaneously.
y + 9 = 7, here that the value of y is not given. So it is true for y = -2 and false for any other value of y. Hence, it is not a statement.
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Question 1291 Mark
Write the negation of the following simple statement:
2 is not a prime number.
Answer
2 is a prime number.
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Question 1301 Mark
Find the component statements of the following compound statements.
Two lines in a plane either intersect at one point or they are parallel.
Answer
p: Two line is a plane intersect at one point.
q: Two lines in a plane are parallel.
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Question 1311 Mark
Determine the contrapositive of the following statements:
If Ravish skis, then it snowed.
Answer
If it did not snow, then Ravish does not ski.
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Question 1321 Mark
Determine the contrapositive of the following statements:
Only if he does not tire will he win.
Answer
If he tires, then he will not win.
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Question 1331 Mark
Form the biconditional statement p ↔ q, where.
p: A triangle is an equilateral triangle.
q: All three sides of a triangle are equal.
Answer
p ⟷ q: A triangle is an equilateral triangle if and only if all three sides of triangle are equal.
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Question 1341 Mark
For the following statements, determine whether an inclusive "OR" or exclusive "OR" is used. Give reasons for your answer.
To entry a country, you need a passport or a voter registration card.
Answer
Inclusive OR is used because a person can have both passport as well as voter registration card.
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Question 1351 Mark
Determine the contrapositive of the following statements:
Only if Max studies will he pass the test.
Answer
If Max does not study, then he will not pass the test.
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Question 1361 Mark
Rewrite the following statements in the form "p if and only if q".
p: If you watch television, then your mind is free and if your mind is free, then you watch television.
Answer
You watch television if and only if your mind is free.
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Question 1371 Mark
Rewrite the following statements in the form of conditional statement:
You will get a sweet dish after the dinner.
Answer
q if p ⇒ If take the dinner, then you will get sweet dish.
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Question 1381 Mark
Show that the following statement is true by the method of contrapositive
p: "If $x$ is an integer and $x^2$ is odd, then $x$ is also odd"
Answer
Let $q$ and $r$ be the statements given by
$q:$ lf $x$ is an integer and $x^2$ is odd
$r: x$ is an odd integer.
Then, $p:$ " lf $q$, thenr."
If possible, let r be false. Then,
$r$ is false
$\Rightarrow x$ is not an odd integer
$\Rightarrow x$ is an even integer
$\Rightarrow x = (2n)$ for some integer $n$
$\Rightarrow x^2 = 4n^2$ 
$\Rightarrow x^2$​​​​​​​^ is an even integer
$\Rightarrow q$ is false.
Thus, $r$ is false $\Rightarrow q$ is false.
Hence, $p$: "if $q$, then $r$" is a true statement.
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Question 1391 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 contradition.
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 $r.$
Metnod of contradiction: If possible, let p be not true. Then,
$p$ is not true
$\Rightarrow $ -pis true
$\Rightarrow -(p \Rightarrow r)$ is true
$\Rightarrow q$ and $-r$ is true
$\Rightarrow x$ is a real number such that $x^3 + x = 0$ and $x = 0$
$\Rightarrow\text{x}=0$ and $\text{x}\not=0$
This a contradiction.
Hence, $p$ is true.
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Question 1401 Mark
Determine the contrapositive of the following statements:
If $x$ is an integer and $x^2$ is odd, then $x$ is odd.
Answer
If $x$ is even, then $x^2$ is even.
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Question 1411 Mark
Write the negation of the following statements:
q: For every real number x, either x > 1 or x < 1.
Answer
q: For every real number x, either x > 1 or x < 1.
q: At least for one real number x, neither x > 1x > 1 nor x < 1x < 1.
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Question 1421 Mark
Write the negation of the following statements:
For every $\text{x}\in\text{N},\text{x}+3<10$
Answer
The Negation of the statement:
For every $\text{x}\in\text{N},\text{x}+3<10$
There exists $\text{x}\in\text{N}$ such that $\text{x}+3\geq10$
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Question 1431 Mark
Some even integers are prime.
Answer
Negation of the given statement:
Some integers are not prime.
Or
No even integer is prime.
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Question 1451 Mark
Find the component statements of the following compound statements:
The earth is round or the sun is cold.
Answer
The component statements of the given compound statement are:
The earth is round.
The sun is cold.
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Question 1461 Mark
Translate the following statement into symbolic form:
Rahul passed in Hindi and English.
Answer
p: Rahul passed in Hindi.
q: Rahul passed in English.
p ∧ q: Rahul passed in Hindi and English.
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Question 1471 Mark
Which of the following statements are true and which are false? In each case give a valid reason for saying so:
s: If x and y are integers such that x > y, then -x < -y.
Answer
True. Because, for any two integers, if x - y is positive then -(x - y) is negative.
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Question 1481 Mark
Identify the Quantifiers in the following statement:
There exists a triangle which is not an isosceles triangle.
Answer
Quantifier are the phrases like ‘There exists’ and ‘For every1, ‘For all’ etc.
There exists.
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Question 1491 Mark
Write the negation of the following statements:
It rained on July 4, 2005.
Answer
Negation of the given statement:
It is not true that it rained on July 4, 2005.
Or
It did not rain on July 4, 2005.
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Question 1501 Mark
Find the component statements of the following compound statements.
The number 100 is divisible by 3, 11 and 5.
Answer
p: 100 is divisible by 3.
q: 100 is divisible by 11.
r: 100 is divisible by 5.
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1 Marks Question - Page 3 - MATHS STD 11 Science Questions - Vidyadip