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Practice MCQ Questions and answers on Chemistry-GK

Learn and practice General Knowledge questions and answers on Chemistry with very easy and understandable explanations. GK questions are very helpful different type of competitive exams. Page-4 section-2

Each section contains 100 MCQs on Chemistry .
31
A potato tuber has been cut into two halves. A few drops of iodine solution are placed on the cut surface of one of the halves. What colour change will be noticed?
Discuss
Answer & Solution
Answer: Option A
Solution:
The Iodine test is used to test for the presence of starch. Iodine solution — iodine dissolved in an aqueous solution of potassium iodide — reacts with the starch producing a purple black colour.
32
An electrochemical cell which is used as a source of direct electrical current at constant voltage under standard conditions is called a :
Discuss
Answer & Solution
Answer: Option B
Solution:
A Galvanic cell, also known as battery, is an electrochemical cell that derives electrical energy from spontaneous redox reactions taking place within the cell. It is typically used as a source of electrical power. By their nature, they produce direct current. A battery is a set of galvanic cells that are connected in parallel.
33
The metals commonly used for electroplating are
Discuss
Answer & Solution
Answer: Option B
Solution:
The metals commonly used for electroplating are Chromium, Copper and Nickel.
34
In galvanization, iron is coated with
Discuss
Answer & Solution
Answer: Option B
Solution:
Galvanisation or galvanization (or galvanizing as it is most commonly called) is the process of applying a protective zinc coating to iron or steel, to prevent rusting. The most common method is hot dip galvanizing, in which steel sections are submerged in a bath of molten zinc.
35
The process of improving the quality of rubber by heating it with sulphur is called
Discuss
Answer & Solution
Answer: Option A
Solution:
The process of improving the quality of rubber by heating it with sulphur is called vulcanization.
36
Rusting of iron takes place due to
Discuss
Answer & Solution
Answer: Option A
Solution:
Dunstan states that rusting of iron takes place in the presence of water and oxygen when every trace of carbonic acid has been removed.
37
Combustion of a candle is a/an
Discuss
Answer & Solution
Answer: Option D
Solution:
In theory, a candle is made of a solid hydrocarbon called paraffin. When the solid burns, the hydrocarbon reacts with oxygen to form carbon dioxide and water. The reaction is exothermic, meaning it releases heat to the atmosphere along with the other products.
38
Which of the following is chiefly present in LPG (Liquefied Petroleum Gas) ?
Discuss
Answer & Solution
Answer: Option D
Solution:
LPG is composed mainly of propane and butane, while natural gas is composed of the lighter methane and ethane.
39
Candle is a mixture of
Discuss
Answer & Solution
Answer: Option A
Solution:
Most candles are made from paraffin wax, a byproduct of petroleum refining. Candles can also be made from microcrystalline wax, beeswax (a byproduct of honey collection), gel (a mixture of polymer and mineral oil), or some plant waxes (generally palm, carnauba, bayberry, or soybean wax).
40
Coal is formed from
Discuss
Answer & Solution
Answer: Option D
Solution:
Coal is mostly carbon with variable amounts of other elements; chiefly hydrogen, sulphur, oxygen, and nitrogen. Coal is formed when dead plant matter decays into peat and is converted into coal by the heat and pressure of deep burial over millions of years.