Assertion (A) & Reason (B) MCQ

MCQ 11 Mark

Assertion (A): A certain element X, forms three binary compounds with chlorine-containing 59.68 %, 68.95 % and 74.75 % chlorine respectively. These data illustrate the law of multiple proportions.
Reason (R): According to law of multiple proportions, the relative amounts of an element combining with some fixed amount of a second element in a series of compounds are the ratios of small whole numbers.

✓
Both A and R are true and R is the correct explanation of A
B
Both A and R are true hut R is not the correct explanation of A.
C
A is true but R is false.
D
A is false but R is true.

Answer

Correct option: A.

Both A and R are true and R is the correct explanation of A

(a) Both A and R are true and R is the correct explanation of A .
Explanation: Both A and R are true and R is the correct explanation of A .

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MCQ 21 Mark

Assertion (A): The energy of quantum of radiation is given by $E = h \nu$.
Reason (R): Quantum in the energy equation signifies the principal quantum number.

A
Both A and R are true and R is the correct explanation of A
B
Both A and R are true hut R is not the correct explanation of A.
✓
A is true but R is false.
D
A is false but R is true.

Answer

Correct option: C.

A is true but R is false.

(c) A is true but R is false.
Explanation: $E = h \nu$, where $h =$ Planck's constant $=6.626 \times 10^{-34} Js$ and $\nu=$ frequency. Quantum is the smallest quantity of energy that can be emitted (or absorbed). According to Planck' theory, energy is emitted in integral multiples of $h \nu$, e.g. $h \nu$, 2 h $\nu$, 3h $\nu$ etc.

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MCQ 31 Mark

Assertion (A): Acetylene is acidic in nature.
Reason (R): Acetylene is sp hybridised.

A
Both A and R are true and R is the correct explanation of A
✓
Both A and R are true hut R is not the correct explanation of A.
C
A is true but R is false.
D
A is false but R is true.

Answer

Correct option: B.

Both A and R are true hut R is not the correct explanation of A.

(b) Both A and R are true but R is not the correct explanation of A .
Explanation: The acidic nature in acetylene is described on the basis of higher electronegativity of sp hybridized carbon atom which pulls more effectively the C - H bond pair to lose $H ^{+}$.

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MCQ 41 Mark

Assertion (A): The IUPAC name for $CH _3 CH = CH - C \equiv CH$ is pent-3-en-1-yne and not pent-2-en-4-yne.
Reason (R): While deciding the locants for double and triple bonds, lowest sum rule is always followed.

✓
Both A and R are true and R is the correct explanation of A.
B
Both A and R are true but R is not the correct explanation of A.
C
A is true but R is false.
D
A is false but R is true.

Answer

Correct option: A.

Both A and R are true and R is the correct explanation of A.

(a) Both A and R are true and R is the correct explanation of A.
Explanation: When double and triple bonds are presently lowest sum rule is followed thus in $\stackrel{5}{ C } H _3 \stackrel{4}{ C } H =\stackrel{3}{ C } H -\stackrel{2}{ C }=\stackrel{1}{ C } H$ Sum of locants $(1+3)=4$.
$
\text { In } CH_1 \underset{2}{CH}=\underset{3}{CH}-\underset{4}{C} \equiv \underset{5}{CH}
$
Sum of locants $(2+4)=6$
So it is named as pent-3-en-1-yne.

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Chemistry Assertion (A) & Reason (B) MCQ

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