Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination. These questions are part of GKToday’s 35000+ MCQs Bank Course in GKToday Android App
31. Which one out of the following helps in burning?
[A] Oxygen
[B] Carbon monoxide
[C] Nitrogen
[D] Carbon dioxide
Show Answer
Correct Answer: A [Oxygen]
Notes:
Joseph Priestley, the English chemist, also prepared oxygen in 1774 by focusing the sun’s rays with the help of a lens on mercuric oxide. Its elemental nature was, however, established by the French chemist, Lavoisier proving its necessity in burning.
32. Which among the following is used to dilute oxygen in the gas cylinders used by divers?
[A] Krypton
[B] Argon
[C] Helium
[D] Neon
Show Answer
Correct Answer: C [Helium]
Notes:
Helium is used to dilute the oxygen and nitrogen to reduce possible bending effects. Helium is the gas of choice to use because it is an inert gas, is thinner, therefore more compressible than air, and its narcotic properties are negligible in comparison to nitrogen.
33. Calcium salts used as fertilizer is:
[A] Calcium Carbide
[B] Calcium Carbonate
[C] Calcium Cyanide
[D] Calcium Sulphate
Show Answer
Correct Answer: D [Calcium Sulphate]
Notes:
Sulphur (as sulphate) is a major plant nutrient, and is essential for crop growth. Calcium Sulphate (gypsum) is used to improve soil quality. Calcium sulphate acts as a pH buffer, which can contribute to neutralizing both soil alkalinity and acidity. It is mainly used for the reclamation of sodic soils through ion exchange (calcium replacing sodium).
34. Which alloy is made of essentially copper and tin?
[A] Brass
[B] Bronze
[C] Solder
[D] Ranga
Show Answer
Correct Answer: B [Bronze]
Notes:
Bronze is an alloy of copper and tin. It is one of the earliest metals known to man. Bronze is used in architecture for structural and design elements, for bearings because of its friction properties, and as phosphor bronze in musical instruments, electrical contacts, and ship propellers.
35. Which of the following is a major component of German silver?
[A] Tin
[B] Copper
[C] Silver
[D] Chlorine
Show Answer
Correct Answer: B [Copper]
Notes:
German Silver (also known as New Silver, Nickel Brass, etc) is a copper alloy with nickel and often zinc. The usual formulation is 60% copper, 20% nickel and 20% zinc. It is named for its silvery appearance, but it contains no elemental silver unless plated.
36. Which of the following elements is an actinide?
[A] Ytterbium
[B] Lutetium
[C] Curium
[D] Erbium
Show Answer
Correct Answer: C [Curium]
Notes:
Curium (Cm) is a synthetic chemical element of the actinoid series of the periodic table, atomic number 96. This element of the actinide series was named after Marie and Pierre Curie – both were known for their research on radioactivity. Curium is a hard, dense, silvery metal with a relatively high melting point and boiling point for an actinide.
37. Which of the following elements is present in antiperspirant deodorant?
[A] Aluminium
[B] Iron
[C] Copper
[D] Sodium
Show Answer
Correct Answer: A [Aluminium]
Notes:
Antiperspirants contain antiperspirant actives–usually aluminum salts, which reduce the release of sweat from the sweat glands as they form temporary gel plugs in the most upper parts of the sweat pores. These plugs are removed over time by mechanical action and the natural skin renewal process.
38. Antacids are found in drugs that give relief to:
[A] Eye sight
[B] Stomach ache
[C] Acne
[D] Headache
Show Answer
Correct Answer: B [Stomach ache]
Notes:
An antacid is a substance which neutralizes stomach acidity. Antacids such as magnesium hydroxide are taken by mouth to relieve heartburn, the major symptom of gastro-esophageal reflux disease, or acid indigestion which are a few of the common terms used to describe digestive upset.
39. Water gas is the combination of:
[A] CO and H2
[B] CO2 and H2
[C] CO and H2O
[D] CO2 and CO
Show Answer
Correct Answer: A [CO and H2]
Notes:
Water gas is a synthetic gas, containing carbon monoxide (CO) and hydrogen gas (H2). It is made by passing steam over a red-hot coke. The reaction between steam and hydrocarbons produce the gas mixture.
40. The gas that causes suffocation and death when coal or coke is burnt in a closed room is:
[A] Methane
[B] Ethane
[C] Carbon monoxide
[D] Carbon dioxide
Show Answer
Correct Answer: C [Carbon monoxide]
Notes:
Exhaust fumes of motor cars, gases produced from coal fire in a closed room and coal gas, all contain carbon monoxide, which is the cause of their poisonous nature. When carbon monoxide is inhaled, it prevents the oxygen from combining with haemoglobin and instead combines itself with hemoglobin to form carboxyhaemoglobin, which is stable compound. This causes oxygen starvation in the body tissues and eventually causes death by suffocation.
