Which of the following curves represents a first-order reaction?

1.

2.

3.

4.

1.

2.

3.

4.

Subtopic: First Order Reaction Kinetics |

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Half-life of substance A following first order kinetics is 5 days. Starting with 100g of A, the amount left after 15 days will be:

1. 25 g

2. 50 g

3. 12.5 g

4. 6.25 g

Subtopic: First Order Reaction Kinetics |

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If 'a' is the initial concentration of a substance that reacts according to zero-order kinetics and k is the rate constant, then the time for the reaction to go to completion is:

1. a/k

2. 2/ka

3. k/a

4. 2k/a

Subtopic: First Order Reaction Kinetics |

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In a first order reaction, time required for completion of 99.9% is X times of half-life (t_{1/2}) of the reaction. When reaction is completed 99.9%, [R]_{n} = [R]_{0} – 0.999[R]_{0} .The value of X is-

1. 5

2. 10

3. 15

4. 20

Subtopic: First Order Reaction Kinetics |

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The reaction of hydrogen and iodine monochloride is given as:

H_{2}(*g*) + 2ICl(*g*) → 2HCl(*g*) + *I*_{2}(*g*)

This reaction is of first order with respect to H_{2}(*g*) and ICl(*g*), for which of the following proposed mechanisms:

Mechanism A:

H_{2}(*g*) + 2ICl(*g*) → 2HCl(*g*) + *I*_{2}(*g*)

Mechanism B:

H_{2}(*g*) + ICl(*g*) →HCl(*g*) + HI(*g*); slow

HI(*g*) + ICl(*g*) →HCl(*g*) + *I*_{2}(*g*); fast

1. B Only

2. A and B both

3. Neither A nor B

4. A only

Subtopic: First Order Reaction Kinetics |

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AIPMT - 2007

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If 75 % of a first-order reaction was completed in 90 minutes, 60 % of the same reaction would be completed in approximately (in minutes):

(Take : log 2 = 0.30 ; log 2.5 = 0.40)

1. 50 min

2. 60 min

3. 70 min

4. 65 min

Subtopic: First Order Reaction Kinetics |

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The correct graphical representation of first-order reaction is:

(a) |
(b) |
||

(c) |
(d) |

1. | (a) and (b) |
2. | (b) and (c) |

3. | (c) and (d) |
4. | (a) and (d) |

Subtopic: First Order Reaction Kinetics |

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Consider the first-order gas-phase decomposition reaction given below.

A(g) → B(g) + C(g)

The initial pressure of the system before the decomposition of A was ${\mathrm{P}}_{\mathrm{i}}$. After the lapse of time t, the total pressure of the system increased by X units and became ${\mathrm{P}}_{\mathrm{t}}$. The rate constant k for the reaction is:

1. $\mathrm{k}=\frac{2.303}{\mathrm{t}}\mathrm{log}\frac{{P}_{\mathrm{i}}}{{P}_{\mathrm{i}}-\mathrm{x}}$

2. $\mathrm{k}=\frac{2.303}{\mathrm{t}}\mathrm{log}\frac{{P}_{\mathrm{i}}}{2{P}_{\mathrm{i}}-{P}_{\mathrm{t}}}$

3. $\mathrm{k}=\frac{2.303}{\mathrm{t}}\mathrm{log}\frac{{P}_{\mathrm{i}}}{2{P}_{\mathrm{i}}+{P}_{\mathrm{t}}}$

4. $\mathrm{k}=\frac{2.303}{\mathrm{t}}\mathrm{log}\frac{{P}_{\mathrm{i}}}{{P}_{\mathrm{i}}+\mathrm{x}}$

Subtopic: First Order Reaction Kinetics |

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For a first-order reaction A → B the reaction rate at a reactant concentration of 0.01M is found to be $2.0\times {10}^{-5}\text{mole}{\mathrm{L}}^{-1}{\text{}\mathrm{s}}^{-1}$. The half-life period of the reaction is:

1. | 300s | 2. | 30s |

3. | 220s | 4. | 347s |

Subtopic: First Order Reaction Kinetics |

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From NCERT

AIPMT - 2005

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