(a) Ethyne, \(C_2H_2\)
For Ethyne, \(C_2H_2\), the molar mass is calculated as:
\[ \text{Molar Mass of Ethyne} = (2 \times \text{Atomic Mass of Carbon}) + (2 \times \text{Atomic Mass of Hydrogen}) \] \[ = (2 \times 12) + (2 \times 1) = 24 + 2 = 26 \, \text{g/mol} \]
(b) Sulphur molecule, \(S_8\)
For Sulphur molecule \(S_8\), the molar mass is calculated as:
\[ \text{Molar Mass of Sulphur} = 8 \times \text{Atomic Mass of Sulphur} \] \[ = 8 \times 32 = 256 \, \text{g/mol} \]
(c) Phosphorus molecule, \(P_4\) (Atomic mass of phosphorus = 31)
For Phosphorus molecule \(P_4\), the molar mass is calculated as:
\[ \text{Molar Mass of Phosphorus} = 4 \times \text{Atomic Mass of Phosphorus} \] \[ = 4 \times 31 = 124 \, \text{g/mol} \]
(d) Hydrochloric acid, \(HCl\)
For Hydrochloric acid \(HCl\), the molar mass is calculated as:
\[ \text{Molar Mass of HCl} = \text{Atomic Mass of Hydrogen} + \text{Atomic Mass of Chlorine} \] \[ = 1 + 35.5 = 36.5 \, \text{g/mol} \]
(e) Nitric acid, \(HNO_3\)
For Nitric acid \(HNO_3\), the molar mass is calculated as:
\[ \text{Molar Mass of Nitric Acid} = \text{Atomic Mass of Hydrogen} + \text{Atomic Mass of Nitrogen} + (3 \times \text{Atomic Mass of Oxygen}) \] \[ = 1 + 14 + (3 \times 16) = 1 + 14 + 48 = 63 \, \text{g/mol}\]