Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. Which among the following is the objective of the Methyl tert-butyl ether (MTBE) mixing with Petroleum?
[A] Raise Octane Number
[B] Antioxidant Stabilizer
[C] Lead Scavanger
[D] Fuel Dye
Show Answer
Correct Answer: A [Raise Octane Number ]
Notes:
MTBE is a gasoline additive, used as an oxygenate to raise the octane number. Its use is controversial in the US and declining in that country in part because of its occurrence in groundwater and legislation favoring ethanol.
2. What happens to the weight of Iron, when it rusts?
[A] Increases for long time
[B] Decreases then increases
[C] Increases then decreases
[D] Remains the same
Show Answer
Correct Answer: C [Increases then decreases]
Notes:
When iron or any other metal oxidizes, oxygen from the air combines with the iron to make iron oxide or rust. So, weight of the bar increases, due to the increased weight of oxygen which has combined with the iron. over time, the weight of the iron bar will tend to decrease, due to factors related more to erosion than to chemistry.
3. Which among the following is the property of Tungsten which makes it eligible to use in the bulbs?
[A] highest melting point
[B] highest resistance
[C] Highest malleability
[D] All are correct
Show Answer
Correct Answer: A [highest melting point]
Notes:
The electric heating is also used to produce light, as in an electric bulb. Here, the filament must retain as much of the heat generated as is possible, so that it gets very hot and emits light. It must not melt at such high temperature. A strong metal with high melting point such as tungsten (melting point 3380°C) is used for making bulb filaments. The filament should be thermally isolated as much as possible, using insulating support, etc. The bulbs are usually filled with chemically inactive nitrogen and argon gases to prolong the life of filament. Most of the power consumed by the filament appears as heat, but a small part of it is in the form of light radiated.
4. Which among the following of a catalyst does not change at the end of a reaction?
[A] Quantity
[B] Chemical Composition
[C] Both Quantity and Chemical com position
[D] None of the above
Show Answer
Correct Answer: C [Both Quantity and Chemical com position]
Notes:
A catalyst is a substance that increases the rate of a chemical reaction without undergoing any permanent change itself. At the end of the reaction, a catalyst retains its original quantity and chemical composition. This property allows it to be used repeatedly in reactions. For example, enzymes, which are biological catalysts, remain unchanged after facilitating biochemical reactions.
5. Which among the following will emit maximum mass of carbon dioxide , when the same quantity is burnt of all of them?
[A] Kerosene
[B] Natural Gas
[C] Gasoline
[D] Propane
Show Answer
Correct Answer: A [Kerosene]
Notes:
The carbon content of Kerosene is higher than the other fuels mentioned in the option, that is why it will emit maximum mass of carbon dioxide, when the same quantity is burnt.
6. Which of the following chemicals is used as a molecular sieve to filter common salts from seawater to produce potable water?
[A] Graphene oxide
[B] Phosgene
[C] Sodium hypochlorite
[D] Calcium carbonate
Show Answer
Correct Answer: A [ Graphene oxide]
Notes:
Graphene oxide is used as a molecular sieve to filter common salts from seawater to produce potable water.
7. What do we call the energy required to remove loosely bound electron from an atom?
[A] Excitation energy
[B] Atom energy
[C] Ionization energy
[D] Shell energy
Show Answer
Correct Answer: C [Ionization energy]
Notes:
Ionization energy is the quantity of energy required to remove loosely bound electron from an atom.
8. Which of the following element is NOT an alkaline earth metal?
[A] Magnesium
[B] Strontium
[C] Barium
[D] Beryllium
Show Answer
Correct Answer: D [Beryllium]
Notes:
The elements of Group 2 include beryllium, magnesium, calcium, strontium, barium and radium. These elements with the exception of beryllium are commonly known as the alkaline earth metals.
9. Choose the incorrect statement:
[A] Epsom salt is an ore containing Sodium
[B] Bauxite is an ore of Aluminium
[C] Asbestos is an ore containing Calcium
[D] Milarite mineral contains Nickel
Show Answer
Correct Answer: A [Epsom salt is an ore containing Sodium]
Notes:
Epsom salt is an ore containing Magnesium. It is also known as the heptahydrate sulfate mineral. Its chemical formula is MgSO4·7H2O.
10. Which of these industrial processes is used for production of aluminium from alumina?
[A] Vunyukov process
[B] Hall–Heroult process
[C] Betts process
[D] None of the above
Show Answer
Correct Answer: B [Hall–Heroult process]
Notes:
The Hall–Heroult process is the major industrial process for production of aluminium. It involves dissolving aluminium oxide in molten cryolite and electrolysing the molten salt bath to get pure aluminium.
