The Language of Chemistry — CHEMISTRY STD 9 — Question

What are electrochemical reactions? Support your answer by two examples.

How many electrons will weigh as much as one atom of hydrogen?

The table below shows the elements from P to T, such that a pair of elements is an isotope. Identity the pair and give a reason for your choice:

Elements	No. of protons	No. of neutrons	No. of electrons
P	11	12	11
Q	12	12	12
R	11	13	11
S	13	14	13
T	14	14	14

Under what conditions can hydrogenbe made to combine with sulphur?
Name the products and write the equation for the reaction.

Correct the following statement:
The boiling point of water is 273 K.

Name the metal which on heating reacts with steam, but reaction is reversible.

MNO₃ is the formula of nitrate of a metal M. Write down the formula of:
Oxide of M

Normally, solubility of crystalline solid increases with temperature. Does it increase uniformly in all cases? Name a substance whose solubility:
Increases gradually with temperature.

Based on the reactions of water on metals, arrange the following metals in increasing order of reactivity: iron, sodium, magnesium, zinc, calcium