Fill in the blanks from the choices given in brackets:

(i) The energy required to remove an electron from a neutral isolated gaseous atom and convert it into a positively charged gaseous ion is called ………….. (electron affinity, ionisation potential, electronegativity)

(ii) The compound that does not have a lone pair of electrons is ………….. (water, ammonia, carbon tetra chloride)

(iii) When a metallic oxide is dissolved in water, the solution formed has a high concentration of ………….. ions. (H⁺, H₃O⁺, OH^-)

(iv) Potassium sulphite on reacting with hydrochloric acid releases ………….. gas. (Cl₂, SO₂, H₂S)

(v) The compound formed when ethene reacts with Hydrogen is ………….. (CH₄, C₂H₆, C₃H₈)

Choose the correct answer from the options given – If the molecular formula of an organic compound is C₁₀H₁₈ it is –

(i) Alkene
(ii) Alkane
(iii) Alkyne
(iv) Not a hydrocarbon

State which of the following is a common characteristic of a covalent compound.

1. High melting point
2. Consists of molecules
3. Always soluble in water
4. Conducts electricity when it is in the molten state.

To increase the pH value of a neutral solution, we should add:

1. an acid
2. an acid salt
3. an alkali
4. a salt