All Free Chemistry MCQs with Answers

• A. one sigma bond, two pi bonds
• B. one sigma bond, four pi bonds
• C. two sigma bonds, four pi bonds
• D. three sigma bonds, two pi bonds

Explanation: Hence ethyne has one sigma bond formed by carbon carbon over lapping and the other two sigma bonds are formed by carbon hydrogen…

• A. He2+
• B. H2-
• C. H2+
• D. H2-2

Explanation: MOLECULAR ORBITAL THEORY: It states that all the atoms tend to combine together and form molecular orbitals.

• A. sp2 - sp
• B. sp2 - sp2
• C. sp3 - sp2
• D. sp - sp

Explanation: The correct answer is sp2 - sp2. In aldehydes and ketones, the carbonyl carbon atom is sp2 hybridized.

• A. 6
• B. 9
• C. 11
• D. 4

Explanation: The molecule CH2=CH-CH=CH2 consists of four carbon atoms and four hydrogen atoms.

• A. CaF2
• B. MgO
• C. KCI
• D. H2

Explanation: Covalent bond is a chemical bond that involves the sharing of electrons,options A, B and C all show ionic bonds, therefore the correct…

• A. It would be disproportion
• B. It would be ratio active
• C. It violates the pauli exclusion principle
• D. No H-H bond would form

Explanation: H22+ cannot be formed as it will be a very unstable structure due to the fact that there would be no bond between H-H

• A. 1/2
• B. 1
• C. 2
• D. 1.5

Explanation: The bond order of H2+ is 1/2. This means that the molecule has a half-filled bonding orbital.

• A. 4.0 x 10^-4 M
• B. 2.0 x 10^-2 M
• C. 8.0 x 10^-4 M
• D. 2.0 x 10^-4 M

Explanation: The solubility product (Ksp) of a salt AB that ionizes as AB = A+ + B- is given as 4.0 x 10-4.

• A. Increases with increase in temperature
• B. Decreases with increase in temperature
• C. Solubility does not change
• D. In some cases it increases while in others it decreases

Explanation: In exothermic reactions, heat energy is released when the solute dissolves in a solution.

• A. 10-10
• B. 10-20
• C. 10-5
• D. 10-6

Explanation: The solubility product constant (Ksp) for BaSO4 at 25°C is given as 1 x 10-10.

• A. Solution will be saturated
• B. Precipitation will occur
• C. Solution will be super saturated
• D. No precipitation will occur

Explanation: Option D is correct. The ionic product is less than the solubility product, meaning the solution contains fewer ions than it could have at…

• A. Deliquescence
• B. Fluorescence
• C. Phosphorescence
• D. Solvent extraction

Explanation: Solvent extraction is used for separation of mixtures

• A. Iodine is extracted from CCl4 layer by water
• B. Iodine is extracted from aqueous layer by CCl4
• C. Iodine is more soluble in water than CCl4
• D. The value of K depends on the amount of Iodine added

Explanation: Iodine vastly prefers to dissolve in CCl4 , thus it migrates from the aqueous (H2O) phase into the non-aqueous (CCl4) phase , thus we say…

• A. Ethylenediamine
• B. potassium ferrocyanide
• C. dimethylglyoxime
• D. potassium permanganate

Explanation: When identifying Ni+2 ions, dimethylglyoxime is the reagent of choice. Adding dimethyl glyoxime to a solution of Ni+2 ions along with…

• A. Hydroquinone
• B. Sodium thiosulphate
• C. Pyfogallal
• D. AgBr

Explanation: Sodium thiosulfate (sodium hyposulfite), Na2S2O3, is used by photographers to fix developed negatives and prints; it acts by dissolving…

• A. excited atoms
• B. Excited molecules
• C. Ground state molecules
• D. Ground state atoms

Explanation: Excited atoms: When atoms are excited, either by heating or by other means such as electrical discharge, they absorb energy and transition…

• A. Mass spectrometer
• B. Cyclotron
• C. Betatron
• D. Reactor

Explanation: The mass spectrometer is a device commonly used for the detection and analysis of isotopes.

• A. Mass spectroscope
• B. Atomic spectroscope
• C. Spectrophotographic analyzer
• D. Spectrophotometer

Explanation: A mass spectroscope is an instrument used to determine the weight (mass) of a proton as well as positive ions.

• A. Sulphate radical
• B. Chloride radical
• C. Nitrate radical
• D. None of the above

Explanation: The brown ring test is a qualitative analysis technique used to detect the presence of nitrate ions.

• A. Imethylglyoxime
• B. Tollen's reagent
• C. Nessler's reagent
• D. Magneson reagen

Explanation: Nessler's reagent can be used to detect the presence of NH4+ ions in water as brown ppt is formed. Therefore the correct answer will be C.