All Free Chemistry MCQs with Answers

• A. CO2 and SO2
• B. BF3 nad NH3
• C. MgCI2 and AICI3
• D. CH4 and SiH4

Explanation: The shape of molecules can be predicted by VSEPR theory. According to this theory the shapes or geometry of a molecule or ion depends on…

• A. NH3
• B. PH3
• C. PCL3
• D. BCL3

Explanation: Electron-deficient compounds are those that have fewer electrons than what would be expected based on the octet rule or the number of…

• A. Ionic
• B. Covalent
• C. Co-ordinate covalent
• D. All of them

Explanation: An ionic bond forms between the NH4 + and Cl - ions in an NH 4 Cl molecule, as well as three covalent bonds between one atom N and three…

• A. HgCl2
• B. SnCl2
• C. C2H2
• D. NO2

Explanation: NO2: This option is correct. NO2 (nitrogen dioxide) has a linear molecular geometry and is isostructural with CO2.

• A. CH3 NH2
• B. PH3
• C. H2O
• D. CH2(NH2)CH2(NH2)

Explanation: Ethylene diamine is a bidentate ligand as it has two Nitrogens, each containing a lone pair of electrons that they can donate to form two…

• A. Linear
• B. V shape
• C. Tetragonal
• D. Triangular

Explanation: The correct molecular shape for a molecule with two sigma bond pairs and one lone pair is V shape or bent.

• A. Tetrahedral shape
• B. Square planar shape
• C. Trigonalbipyramidal shape
• D. Octahedral shape

Explanation: Tetrahedral and Square planar have 4 bonding pairs, trigonal bipyramidal = 5 coordination number whereas octahedral = 6 coordination…

• A. CH4
• B. H2O
• C. SO2
• D. O2

Explanation: C is the correct option as the electronic structure of the SO2 molecule is best represented as a resonance hybrid of two equivalent…

• A. Small size of oxygen atom
• B. Greater electronegativity of oxygen atom
• C. Oxygen contains 2 lone pair of electrons
• D. All of the above

Explanation: The bond angle in H2S is less than in H2O due to the smaller size of oxygen and the presence of two lone pairs of electrons on the oxygen…

• A. Industries
• B. Transportation
• C. Mining Industry
• D. Agricultural and municipal wastage

Explanation: Contamination of water bodies is called water pollution. Pakistan is an agricultural country.

• A. carbonates of Ca2+ and Mg2+ ions
• B. Bicarbonates of Ca2+ and Mg2+ ions
• C. sulphates of Na+ and Mg2+ ions
• D. chlorides of Ca2+ and Mg2+ ions

Explanation: The presence of soluble salts of calcium and magnesium, i.e., sulfates and chlorides of calcium and magnesium, causes permanent hardness…

• A. Ca(NO3)2
• B. MgCl2
• C. Al2(SO4)3
• D. Ca(OH)2

Explanation: In water treatment, coagulants like Al2(SO4)3 (aluminum sulfate) are used to remove impurities by causing them to aggregate for easier…

• A. 6.0 to 7.0
• B. 7.0 to 8.5
• C. 4.5 to 6.0
• D. 8.5 to 9.0

Explanation: It is recommended that the pH of drinking water should be between 6.5-8.5 on a scale that ranges from 0 - 14, hence the answer will be B.

• A. COD
• B. TOC
• C. BOD
• D. TDS

Explanation: Biochemical oxygen demand (BOD) is a chemical procedure for determining the amount of dissolved oxygen needed by microorganisms in a body…

• A. An Iodide compound
• B. A bromide compound
• C. A chloride compound
• D. A fluoride compound

Explanation: Fluoride is a compound that helps prevent tooth decay by strengthening tooth enamel and making it more resistant to acid attacks from…

• A. By adding bacteria to the water
• B. Adding chemical oxidizing agent
• C. Both (A) and (B)
• D. None of the above

Explanation: To check the Chemical Oxygen Demand (COD) of water, you typically add bacteria and an oxidizing agent to the water sample.

• A. Acidic
• B. Crystalline
• C. Amorphous
• D. Neutral

Explanation: White lead, like most pigments precipitated from solution, sets as an amorphous solid: its particles have no long-range ordered lattice…

• A. Xenon
• B. Radon
• C. Krypton
• D. Argon

Explanation: Radon is the only noble gas with no stable isotope: radon-222 is an alpha emitter with a half-life of about 3.8 days, produced in the…

• A. p= 18, n= 15
• B. p=16, n=17
• C. p=16, n=16
• D. p=17, n=16

Explanation: Sulphur has atomic number 16, so its nucleus holds 16 protons whatever the ion's charge. Mass number 33 gives neutrons = 33 - 16 = 17.

• A. 14N
• B. 14N+
• C. 12C
• D. 13C

Explanation: Carbon-14 has 6 protons, 8 neutrons and 6 electrons. Nitrogen-14 has 7 protons and 7 neutrons, and the singly charged ion N-14 positive…