For the reaction X + 2Y → P, the differential form equation of the rate law is : (A) (2d[P])/(dt)=(-d[Y])/(dt) (B) (-d[P])/(dt)=(-d[X])/(dt) (C) (+d[X])/(dt)=(-d[P])/(dt) (D) (-2d[Y])/(dt)=(+d[P])/(dt)

ChemistryCBSE Class 12 · Board exam 2024, set 56/1/1 · 1 mark · MCQ

CBSE Class 12 Chemistry 2024: question 5

Set in the CBSE Class 12 board exam of 2024, paper 56/1/1, section A, question 5, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q5 · 1 mark · MCQChemical Kinetics

For the reaction $X + 2Y \to P$ , the differential form equation of the rate law is :

(A) $\frac{2 d [ P ]}{d t} = \frac{- d [ Y ]}{d t}$
(B) $\frac{- d [ P ]}{d t} = \frac{- d [ X ]}{d t}$
(C) $\frac{+ d [ X ]}{d t} = \frac{- d [ P ]}{d t}$
(D) $\frac{- 2 d [ Y ]}{d t} = \frac{+ d [ P ]}{d t}$

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 56/1/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

Divide each rate of change by its stoichiometric coefficient.

Hint 2

Reactants carry a minus sign and products a plus sign.

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

For X + 2Y → P: Rate $= - \frac{d [ X ]}{d t} = - \frac{1}{2} \frac{d [ Y ]}{d t} = + \frac{d [ P ]}{d t}$ .
Multiplying the Y and P terms by 2 gives $2 \frac{d [ P ]}{d t} = - \frac{d [ Y ]}{d t}$ , which is option (A).
1 mark

Answer: Option (A)

Where the marks are

Writes the rate expression with correct stoichiometric factors (1 mark)

Revise the chapter

Chapter: Chemical Kinetics (notes, formulas, where marks are lost and every past question)

Practise this chapterBoard-style questions from Chemical Kinetics, one at a time, marked against the answer key and marking points.Back to the full paper2024 board paper, set 56/1/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.

CBSE Class 12 Chemistry 2024: question 5

Hints

Step-by-step solution

Revise the chapter

More questions from Chemical Kinetics