| 2061 |
In the Arrhenius equation k = A e^(−Ea/RT), what does the factor e^(−Ea/RT) represent? |
Chemistry
Temperature and rate |
Easy |
| 2062 |
A plot of ln k against 1/T for a reaction is a straight line. What is its slope? |
Chemistry
Temperature and rate |
Medium |
| 2063 |
According to collision theory, why do many collisions with enough energy still fail to give products? |
Chemistry
Temperature and rate |
Medium |
| 2064 |
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 |
| 2065 |
What is the ground-state outer electronic configuration of chromium (Z = 24)? |
Chemistry
Transition elements: general properties |
Easy |
| 2066 |
Why is zinc not regarded as a typical transition element? |
Chemistry
Transition elements: general properties |
Easy |
| 2067 |
Which 3d transition element shows the largest number of oxidation states? |
Chemistry
Transition elements: general properties |
Medium |
| 2068 |
Why does copper not liberate hydrogen gas from dilute hydrochloric acid? |
Chemistry
Transition elements: general properties |
Medium |
| 2069 |
Which ion would you expect to act as a strong reducing agent in aqueous solution? |
Chemistry
Transition elements: general properties |
Hard |
| 2070 |
Which ion is colourless in aqueous solution? |
Chemistry
Properties of transition metals |
Easy |
| 2071 |
Which catalyst is used in the contact process for making sulphuric acid? |
Chemistry
Properties of transition metals |
Easy |
| 2072 |
What is the spin-only magnetic moment of Mn²⁺ (Z of Mn = 25)? |
Chemistry
Properties of transition metals |
Medium |
| 2073 |
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 |
| 2074 |
Which property is NOT typical of interstitial compounds of transition metals? |
Chemistry
Properties of transition metals |
Hard |
| 2075 |
What colour change is seen when acidified potassium dichromate acts as an oxidising agent? |
Chemistry
Oxides, oxoanions and important compounds |
Easy |
| 2076 |
Which ore is the starting material for the manufacture of potassium dichromate? |
Chemistry
Oxides, oxoanions and important compounds |
Easy |
| 2077 |
How many electrons are gained per permanganate ion when it acts as an oxidising agent in acidic solution? |
Chemistry
Oxides, oxoanions and important compounds |
Medium |
| 2078 |
What happens when an acid is added to a yellow solution of potassium chromate? |
Chemistry
Oxides, oxoanions and important compounds |
Medium |
| 2079 |
Why is hydrochloric acid not used to acidify KMnO₄ in redox titrations? |
Chemistry
Oxides, oxoanions and important compounds |
Hard |
| 2080 |
What is the most common oxidation state of the lanthanoids? |
Chemistry
Lanthanoids and actinoids |
Easy |