State the term defined by the following sentence:

A soluble base

State the term defined by the following sentence:

The insoluble solid formed when two solutions are mixed together.

State the term defined by the following sentence:

Which of the following methods, A, B, C, D or E is generally used for preparing Copper ($\mathrm{II}$) chloride?

A. Action of an acid on a metal.

B. Action of an acid on an oxide or carbonate.

C. Direct combination.

D. Neutralization of an alkali by an acid.

E. Precipitation (double decomposition).

Which of the following methods, A, B, C, D or E is generally used for preparing Iron ($\mathrm{II}$) chloride?

A. Action of an acid on a metal.

B. Action of an acid on an oxide or carbonate.

C. Direct combination.

D. Neutralization of an alkali by an acid.

E. Precipitation (double decomposition).

Which of the following methods, A, B, C, D or E is generally used for preparing Iron ($\mathrm{III}$) chloride?

A. Action of an acid on a metal.

B. Action of an acid on an oxide or carbonate.

C. Direct combination.

D. Neutralization of an alkali by an acid.

E. Precipitation (double decomposition).

Which of the following methods, A, B, C, D or E is generally used for preparing Lead ($\mathrm{II}$) chloride. 

A. Action of an acid on a metal.

B. Action of an acid on an oxide or carbonate.

C. Direct combination.

D. Neutralization of an alkali by an acid.

E. Precipitation (double decomposition).

Which of the following methods, A, B, C, D or E is generally used for preparing Sodium chloride. 

A. Action of an acid on a metal.

B. Action of an acid on an oxide or carbonate.

C. Direct combination.

D. Neutralization of an alkali by an acid.

E. Precipitation (double decomposition).

Choose the covalent oxide of a metalloid from $\left[{\mathrm{SO}}_2, {\mathrm{SiO}}_2, {\mathrm{Al}}_2{\mathrm{O}}_3, \mathrm{CO}, \mathrm{MgO}, {\mathrm{Na}}_2\mathrm{O}\right]$.