| 61 |
The half-life of a first-order reaction is 10 minutes. What is its rate constant? |
Chemistry
Integrated rate equations |
Easy |
| 62 |
For which order of reaction is the half-life independent of the initial concentration? |
Chemistry
Integrated rate equations |
Easy |
| 63 |
How many half-lives are needed for 75% of a first-order reaction to be completed? |
Chemistry
Integrated rate equations |
Medium |
| 64 |
A zero-order reaction has [R]₀ = 0.2 mol L⁻¹ and k = 0.01 mol L⁻¹ s⁻¹. What is its half-life? |
Chemistry
Integrated rate equations |
Medium |
| 65 |
The acid-catalysed hydrolysis of ethyl acetate behaves as a first-order reaction even though it involves este… |
Chemistry
Integrated rate equations |
Hard |
| 66 |
How does a catalyst increase the rate of a reaction? |
Chemistry
Temperature and rate |
Easy |
| 67 |
In the Arrhenius equation k = A e^(−Ea/RT), what does the factor e^(−Ea/RT) represent? |
Chemistry
Temperature and rate |
Easy |
| 68 |
A plot of ln k against 1/T for a reaction is a straight line. What is its slope? |
Chemistry
Temperature and rate |
Medium |
| 69 |
According to collision theory, why do many collisions with enough energy still fail to give products? |
Chemistry
Temperature and rate |
Medium |
| 70 |
The rate constant of a reaction doubles when the temperature rises from 300 K to 310 K. What is the approxima… |
Chemistry
Temperature and rate |
Hard |
| 71 |
What is the ground-state outer electronic configuration of chromium (Z = 24)? |
Chemistry
Transition elements: general properties |
Easy |
| 72 |
Why is zinc not regarded as a typical transition element? |
Chemistry
Transition elements: general properties |
Easy |
| 73 |
Which 3d transition element shows the largest number of oxidation states? |
Chemistry
Transition elements: general properties |
Medium |
| 74 |
Why does copper not liberate hydrogen gas from dilute hydrochloric acid? |
Chemistry
Transition elements: general properties |
Medium |
| 75 |
Which ion would you expect to act as a strong reducing agent in aqueous solution? |
Chemistry
Transition elements: general properties |
Hard |
| 76 |
Which ion is colourless in aqueous solution? |
Chemistry
Properties of transition metals |
Easy |
| 77 |
Which catalyst is used in the contact process for making sulphuric acid? |
Chemistry
Properties of transition metals |
Easy |
| 78 |
What is the spin-only magnetic moment of Mn²⁺ (Z of Mn = 25)? |
Chemistry
Properties of transition metals |
Medium |
| 79 |
An ion of a 3d metal has a spin-only magnetic moment of 3.87 BM. How many unpaired electrons does it have? |
Chemistry
Properties of transition metals |
Medium |
| 80 |
Which property is NOT typical of interstitial compounds of transition metals? |
Chemistry
Properties of transition metals |
Hard |