CIE Chemistry (US-0439): Specimen Questions with Answers 239 - 240 of 240

Question number: 239

MCQ▾

Question

Water has been contaminated with sea-water.

Which substances can be removed by chlorination and filtration?

Choices

Choice (4) Response

a.

Bacteria, sand and sodium chloride

b.

Bacteria and sand only

c.

Bacteria and sodium chloride only

d.

Sand and sodium chloride only

Answer

a.

Explanation

Correct option is A i. e. bacteria, sand and sodium chloride because Water chlorination is the process of adding chlorine or hypochlorite to water. This method is used to kill certain bacteria and other microbes in tap water as chlorine is highly toxic. In particular, chlorination is used to prevent the spread of waterborne diseases such as cholera, dysentery, and typhoid. Filtration is any of various mechanical, physical or biological operations that separate solids from fluids (liquids or gases) by adding a medium through which only the fluid can pass. The fluid that passes through is called the filtrate.

Question number: 240

MCQ▾

Question

________ can be prepared by the direct synthesis of Magnesium and Oxygen.

Choices

Choice (4) Response

a.

b.

c.

d.

Answer

a.

Explanation

MgO can be prepared by the direct synthesis of Magnesium and Oxygen.