Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination
41.Which of the following was invented by Sir Humphry Davy?
[A] Safety Lamp
[B] Steam Engine
[C] Safety Pin
[D] X-Rays
Correct Answer: A [Safety Lamp]
Notes:
The Davy lamp is a safety lamp for use in flammable atmospheres, invented in 1815 by Sir Humphry Davy. It consists of a wick lamp with the flame enclosed inside a mesh screen.
42.Most liquids that conduct electricity are solutions of acids, base and which of the following?
[A] Aluminium
[B] Copper
[C] Iron
[D] Salts
Correct Answer: D [Salts]
Notes:
Solutions that contain ions are good conductors of electricity, such as, acids, bases, salt water. Tap water, lemon juice and mercury is the best liquid conductor compare with others. Because of any solution to conduct, you need ions or free electrons.
43.Prafulla Chandra Ray, who is known as father of chemical science in India, was founder of India’s first pharmaceutical company. What is name of that company?
[A] Hindustan Pharmaceuticals
[B] Orchid Chemicals & Pharmaceuticals
[C] Indian Drugs and Pharmaceuticals
[D] Bengal Chemicals and Pharmaceuticals
Correct Answer: D [Bengal Chemicals and Pharmaceuticals]
Notes:
Acharya Sir Prafulla Chandra Ray (1861 – 1944) had established first Indian research school in chemistry and is regarded as the father of chemical science in India. He was the founder of Bengal Chemicals & Pharmaceuticals, India’s first pharmaceutical company. He also wrote a book titled “A History of Hindu Chemistry from the Earliest Times to the Middle of Sixteenth Century” , published in 1902.
44.The plum pudding model of atomic structure was given by which scientist?
[A] Rutherford
[B] JJ Thomson
[C] Goldstein
[D] Millikan
Correct Answer: B [JJ Thomson]
Notes:
J.J. Thomson proposed his atomic model soon after his discovery of electrons. Its major postulates were: (1) An atom contains negatively charged particles called electrons embedded uniformly throughout a thinly spread positively charged mass. (2) Since the atom is electrically neutral, the total negative charge of electrons is balanced by the total positive charge. 
Thomson’s model of an atom is popularly known as plum pudding model or apple pie model or watermelon model. Thomson’s model could successfully explain the electrical neutrality of atom. However, it failed to explain how the positively charged particles are shielded from the negatively charged electrons without getting neutralized.
45.Which of the following serve as olfactory indicators to identify acidic or basic solutions?
[A] Onion Juice
[B] Vanilla Extract
[C] Clove Oil
[D] All of Above
Correct Answer: D [All of Above]
Notes:
Olfactory indicator are those substances whose smell can help to distinguish between acids and bases. Onion Juice loses its characteristic smell in Basic solution and retains its smell in Acidic solution; so it serves as olfactory indicator. Similarly, Vanilla extract also loses its smell in basic solution and retains its smell in Acidic solution. Clove oil is also olfactory indicator but its not for weak acids and basic solutions.
46.What percentage of carbon is present in steel?
[A] 0.0 to 2.5
[B] 2.5 to 5.0
[C] 5.0 to 7.5
[D] 7.5 to 10.0
Correct Answer: A [0.0 to 2.5 ]
Notes:
Steel is an alloy made by combining iron and other elements, the most common of these being carbon. When carbon is used, its content in the steel is between 0.2% and 2. 1% by weight, depending on the grade. Other alloying elements sometimes used are manganese, chromium, vanadium and tungsten. Carbon and other elements act as a hardening agent, preventing dislocations in the iron atom crystal lattice from sliding past one another.
47.Which metal does not present in the alloy “German Silver”?
[A] Nickel
[B] Zinc
[C] Copper
[D] Silver
Correct Answer: D [ Silver ]
Notes:
The German silver has long been in existence as it could be traced back to as far back as early 18th century. This Silver was developed in Germany by the German metalworkers in imitation of the Chinese alloys to be used as a substitute for silver since silver is highly expensive. The German silver is also known as the Nickel silver. These terms “German silver” and “Nickel silver” could be used interchangeably. It is a silver-white alloy of Copper, Zinc and Nickel. The German silver does not contain any trace of silver. The German silver is composed of three major elements Copper, Zinc and Nickel and sometimes with a trace of Tin and Lead. These elements vary in percentage with a range of Copper from approximately 50% – 61.6%, Zinc with an approximate range of 17.2& – 19% and Nickel with an approximate range of 21.1% – 30%. Theses compositions are always specified when it comes to commercial alloys. German silver is extensively used because of its hardness, toughness, and resistance to corrosion for articles such as tableware (commonly silver plated), marine fittings, and plumbing fixtures. Because of its high electrical resistance, it is used also in heating coils. It was discovered (early 19th cent.) by a German industrial chemist, E. A. Geitner.
48.
Biogas is composed of Oxygen, Carbon dioxide, Nitrogen, Hydrogen, Methane and Hydrogen Sulphide compounds. Which one of the following compounds forms the majority?
[A] Carbon dioxide
[B] Carbon monoxide
[C] Hydrogen sulphide
[D] Methane
Correct Answer: D [Methane ]
Notes:
Biogas or Gobar gas is produced by the anaerobic digestion or fermentation of biodegradable materials such as biomass, manure, sewage, municipal waste, green waste, plant material, and crops. It comprises primarily methane (CH4) and carbon dioxide (CO2) and may have small amounts of hydrogen sulphide (H2S), moisture and siloxanes. The composition of biogas varies depending upon the substrate composition, as well as the conditions within the anaerobic reactor (temperature, pH, and substrate concentration). Landfill gas typically has methane concentrations around 50%. Advanced waste treatment technologies can produce biogas with 55%–75% methane, which for reactors with free liquids can be increased to 80%–90% methane using in-situ gas purification techniques. As produced, biogas contains water vapour. The fractional volume of water vapour is a function of biogas temperature; correction of measured gas volume for water vapour content and thermal expansion is easily done via simple mathematics which yields the standardized volume of dry biogas.
49.Which one amongst the following is not a GreenHouse gas?
[A] Nitrogen
[B] Carbon dioxide
[C] Carbon Monoxide
[D] Chloro fluorocarbons
Correct Answer: A [Nitrogen]
Notes:
A greenhouse gas (sometimes abbreviated GHG) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. The primary greenhouse gases in the Earth’s atmosphere are water vapour, carbon dioxide, methane, nitrous oxide, and ozone. Nitrous oxide (N2O) gas should not be confused with nitric oxide (NO) or nitrogen dioxide (NO2). Neither nitric oxide nor nitrogen dioxide is greenhouse gases, although they are important in the process of creation of tropospheric ozone which is a greenhouse gas. There are several sources of nitrous oxide, both natural and anthropogenic (human), to the atmosphere with many of these sources difficult to measure. Because of this, there is general agreement that the atmospheric sources and sinks of nitrous oxide are difficult to bring into balance.
50.Which element is used in the manufacture of safety matches?
[A] Phosphorous
[B] Magnesium
[C] Silicon
[D] Sulphur
Correct Answer: A [Phosphorous ]
Notes:
One end of a match is coated with a material that can be ignited by frictional heat generated by striking the match against a suitable surface. The coated end of a match, known as the match “head,” contains either phosphorus or phosphorus sesquisulfide as the active ingredient and gelatin as a binder. The tip of the strike-anywhere match contains phosphorus sesquisulfide, P4S3, a nontoxic, stable compound, which is converted to flammable white phosphorus when the match-head is dragged across a rough surface. (The match-head usually also contains powdered glass to increase the friction.) Once the white phosphorus ignites, it causes potassium chlorate, KClO3, in the match-head to burn, producing molecular oxygen, which further feeds the combustion reaction, until the wooden stick starts to burn. In safety matches, the phosphorus is not in the match-head, but is instead on the side of the box, thus separating the components that are necessary to ignite the match. Dragging the match-head across the rough surface of the box converts some of the red phosphorus into white phosphorus, which ignites the match-head, once again causing potassium chlorate to produce molecular oxygen
