Question

write molecular formula
(a) Chlorine
(b) Oxygen
(c) Common salt
(d) Water
(e) Nitrogen
(f) Hydrogen
(g) Lead sulphide
(h) Calcium oxide
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Answer 1

(a) $\large\rm {Cl}$

(b) $\large\rm {O}$

(c) $\large\rm {NaCl}$

(d) $\large\rm { H_{2} O}$

(e) $\large\rm { N}$

(f) $\large\rm { H_{2}}$

(g) $\large\rm { PbS}$

(h) $\large\rm { CaO}$

Hope it helps you :)

Answer 2

Explanation:

Magnesium is an very reactive metal. When stored, it reacts with oxygen to form a layer of magnesium oxide on its surface. This layer of magnesium oxide is quite stable and prevents further reaction of magnesium with oxygen. The magnesium ribbon is cleaned by sand paper for removing this layer so that the underlying metal can be exposed to air.

2. Write the balanced equation for the following chemical reactions.

(a) Hydrogen + Chlorine → Hydrogen chloride

(b) Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride

(c) Sodium + Water → Sodium hydroxide + Hydrogen

Ans: (a) H2 (g) + Cl2 (g) → 2HCl (g)

(b) 3BaCl2 (s) + Al2(SO4)3 (s) → 3BaSO4(s) + 2AlCl3 (s)

(c) (c) 2Na(s) + 2H2O (l) → 2NaOH (aq) + H2 (g)