Explanation

• Hess's law states that the total enthalpy change of a chemical reaction is the same regardless of whether the reaction takes place in one step or several steps.
• Enthalpy change depends only on the initial reactants and final products, not on the pathway followed by the reaction.
• The law is based on the fact that enthalpy is a state function, meaning its value depends on the initial and final states.

Last verified on 25-10-2026

Explanation

• The addition of HCl to propene is an electrophilic addition reaction.
• The H⁺ ion attacks the double bond first, forming a more stable carbocation intermediate.

Last verified on 25-10-2026

Explanation

• The M²⁺ ion has 24 electrons (2 + 8 + 14 = 24). Since it has lost 2 electrons, the atomic number of M is 26.
• Number of neutrons = Mass number − Atomic number = 56 − 26 = 30.
• Therefore, the nucleus contains 30 neutrons.

Last verified on 25-10-2026

Explanation

• Electrolysis is a process in which electrical energy is used to drive a non-spontaneous chemical reaction.
• It takes place in an electrolytic cell, where an external power source forces electrons to move and drives oxidation-reduction reactions.
• During electrolysis, oxidation occurs at the anode and reduction occurs at the cathode.

Last verified on 25-10-2026

Explanation

• A heterocyclic compound is a cyclic compound whose ring contains at least one atom other than carbon, such as nitrogen, oxygen, or sulfur.
• Indole is a heterocyclic compound consisting of a benzene ring fused with a five-membered nitrogen-containing ring.
• Pyridine is a heterocyclic compound with a six-membered ring containing five carbon atoms and one nitrogen atom.

Last verified on 25-10-2026

Explanation

• A, D, E, and K are fat-soluble vitamins.
• Fat-soluble vitamins are absorbed by the body along with dietary fats.
• They are present in foods that contain fats.
• The body stores these vitamins in the liver and fat tissue when they are not in use. 
• Megadoses of fat-soluble vitamins can be toxic.

Last verified on 25-10-2026

Explanation

Reaction: CaCO3 + 2HCl -> CaCl2 + CO2 + H2O

Given:

CaCO3 = 50g

Actual CO2 = 14.52g

Step 1: Molar mass of CaCO3 = 100 g/mol

Moles of CaCO3 = 50 / 100 = 0.5 mole

Step 2: 1 mole CaCO3 gives 1 mole CO2

So 0.5 mole CaCO3 gives 0.5 mole CO2

Step 3: Molar mass of CO2 = 44 g/mol

Theoretical yield of CO2 = 0.5 x 44 = 22g

Step 4: Percentage yield = (Actual / Theoretical) x 100

= (14.52 / 22) x 100

= 66%

Theoretical yield = 22g

Percentage yield = 66%

Last verified on 25-10-2026

Explanation

• According to Le Chatelier’s principle, adding nitrogen increases the concentration of a reactant, causing the equilibrium to shift to the right.
• The forward reaction consumes nitrogen and hydrogen to produce ammonia (NH₃).
• Therefore, adding more nitrogen increases the amount of ammonia produced as the system reaches a new equilibrium.

Last verified on 25-10-2026

Explanation

• A basic buffer solution consists of a weak base and its conjugate acid.
• It resists changes in pH when small amounts of acid or base are added.
• Ammonia (NH₃) is a weak base.
• When hydrochloric acid (HCl) reacts with excess ammonia, it forms ammonium chloride (NH₄Cl), leaving some unreacted NH₃.
• The mixture contains a weak base (NH₃) and its conjugate acid (NH₄⁺), making it a basic buffer solution.

Last verified on 25-10-2026

Explanation

• A catalyst increases the rate of a chemical reaction by providing an alternative reaction pathway with lower activation energy.
• Activation energy is the minimum energy required for reactants to start a chemical reaction.
• Lower activation energy allows more particles to react successfully in a given time.

Last verified on 25-10-2026