Chemistry MCQs
Chemistry Objective (Multiple Choice) General Knowledge Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examination.
1. Dalton’s name is associated with which of the following terms?
[A] Electron
[B] Proton
[C] Atom
[D] Neutron
Show Answer
Correct Answer: C [Atom]
Notes:
John Dalton introduced the atomic theory into chemistry. The main points of Dalton’s atomic theory are (1) Elements are made of extremely small particles called atoms. (2) Atoms of a given element are identical in size, mass and other properties; atoms of different elements differ in size, mass and other properties.(3) Atoms cannot be subdivided, created or destroyed. (4) Atoms of different elements combine in simple whole-number ratios to form chemical compounds. (5) In chemical reactions, atoms are combined, separated or rearranged.
2. The aqueous solution of which among the following acids is called Vinegar?
[A] Oxalic acid
[B] Citric acid
[C] Acetic acid
[D] Hydrochloric acid
Show Answer
Correct Answer: C [Acetic acid ]
Notes:
Acetic acid (CH3COOH) is a weak organic acid that gives vinegar its sour taste. At household concentrations (5-8% acetic acid), it is a mild acid. Vinegar can be made from a variety of base ingredients including wine, apple cider, rice, or malt. The acetic acid is produced by fermentation of the sugars in these ingredients. The most common type of vinegar in households is white distilled vinegar which is typically 4-7% acetic acid. It has a strong, pungent smell and flavor.
3. 2,4-D, which is sold as a weed killer of the broad-leaved weeds is a synthetic version of __:
[A] Auxin Hormone
[B] Cytokinin Hormone
[C] Xylitol
[D] None of them
Show Answer
Correct Answer: A [Auxin Hormone ]
Notes:
2,4-dichlorophenoxyacetic acid (2,4-dichlorophenoxyethanoic acid) is a synthetic auxin frequently used as a weed killer of broad-leaved weeds. When two herbicides 2,4,5-T and 2,4-D and mixed in equal parts, it is called Agent Orange, which was used by US in Vietnam war.
4. Which among the following compound of barium is used as radio contrast agent for X-ray imaging and other diagnostic procedures and also commonly called as Barium Food?
[A] Barium Carbonate
[B] Barium Sulphate
[C] Barium Bromide
[D] Barium hydroxide
Show Answer
Correct Answer: B [Barium Sulphate]
Notes:
Barium Sulphate is the correct answer. It is used as a radiopaque contrast agent in X-ray imaging because it absorbs X-rays, making it visible on the images. Commonly referred to as “Barium Meal” when ingested for gastrointestinal studies, it helps diagnose conditions like ulcers and tumors. Barium Sulphate is insoluble in water, ensuring it remains in the digestive tract without being absorbed.
5. Buckeyballs are basically the allotropes of _________?
[A] Carbon
[B] Sulfur
[C] Phosphorus
[D] Calcium
Show Answer
Correct Answer: A [Carbon]
Notes:
Buckeyballs, or fullerenes, are allotropes of carbon. Discovered in 1985, they consist of 60 carbon atoms arranged in a spherical shape, resembling a soccer ball. This unique structure contributes to their remarkable properties, including high strength and electrical conductivity. Fullerenes are part of a broader class of carbon allotropes, which also includes graphite and diamond.
6. Which of the following element has the highest first ionization enthalpy?
[A] Magnesium
[B] Strontium
[C] Beryllium
[D] Barium
Show Answer
Correct Answer: C [Beryllium]
Notes:
The alkaline earth metals have low ionization enthalpies due to fairly large size of the atoms. Since the atomic size increases down the group, their ionization enthalpy decreases.
7. How is Aqua regia formed?
[A] by mixing 2 parts of concentrated HCl and one part of concentrated HNO3
[B] by mixing 3 parts of concentrated HCl and one part of concentrated HNO3
[C] by mixing 1 part of concentrated HCl and three parts of concentrated HNO3
[D] None of the above
Show Answer
Correct Answer: B [by mixing 3 parts of concentrated HCl and one part of concentrated HNO3]
Notes:
When three parts of concentrated HCl and one part of concentrated HNO3 are mixed, aqua regia is formed which is used for dissolving noble metals, e.g., gold, platinum.
8. Which of the following is incorrect?
[A] Alloying helps in improving the properties of a metal
[B] An alloy is a heterogeneous mixture of two or more metals
[C] The melting point of an alloy is less than that of pure metals
[D] All of the above
Show Answer
Correct Answer: B [An alloy is a heterogeneous mixture of two or more metals]
Notes:
An alloy is a homogeneous mixture of two or more metals, or a metal and a nonmetal. Alloying helps in improving the properties of a metal. The melting point of an alloy is less than that of pure metals.
9. Which of the following is also known as Alumina?
[A] AlO2
[B] Al2O3
[C] Al2O4
[D] Al2CO2
Show Answer
Correct Answer: B [Al2O3]
Notes:
Alumina is the common name given to aluminum oxide (Al2O3). It is produced from bauxite to get pure aluminium metal.
10. Which of the following is incorrect statement about various ores?
[A] Borax is an ore of Sodium
[B] Dolomite is an ore of Aluminium
[C] The chemical formula of Magnetite is Fe3O4
[D] Flourspar is an ore of Potassium
Show Answer
Correct Answer: D [Flourspar is an ore of Potassium]
Notes:
Fluorite or Fluorspar is an ore of Calcium. It is a mineral composed of calcium fluoride. It belongs to the family of halide minerals.
