Explanation

• In thermodynamics, a system is the part under study.
• Everything outside it is called surroundings.
• Here, the focus is on the gas behavior.
• So, the O₂ gas inside the balloon is the system.
• Freezer and environment act as surroundings.

Last verified on 12-04-2026

Explanation

• A covalent bond forms when atoms share electrons.
• It usually occurs between non-metals.
• Sharing helps atoms achieve stable electron configuration.
• No transfer of electrons occurs.
• Therefore, it is based on electron sharing.

Last verified on 12-04-2026

Explanation

• Bond energy, length, and order describe how strong a chemical bond is.
• Higher bond energy → stronger bond.
• Shorter bond length → stronger bond.
• Higher bond order → stronger bond.
• All three parameters indicate bond strength.

Last verified on 12-04-2026

Explanation

Rate ∝ ^n

If × 4 → Rate × 2:[Reactant]

4ⁿ = 2 → n = 1/2

Last verified on 12-04-2026

Explanation

• Carbon is a tetravalent element.
• It forms 4 covalent bonds in most compounds.
• In C₂H₆O (ethanol or dimethyl ether), carbon still makes 4 bonds.
• Valency is based on bonding capacity, not charge here.
• So, carbon’s valency remains 4.

Last verified on 12-04-2026

Explanation

Use the first law of thermodynamics: ΔU = Q + W

Sign convention:  

Heat added _to_ system: Q = +20 kJ

Work done _on_ system: W = +60 kJ

ΔU = 20 + 60 = 80 kJ

Last verified on 12-04-2026

Explanation

• When two or more substances are physically combined, they form a mixture.
• In a mixture, components retain their properties.
• They can be separated by physical methods like filtration or evaporation.
• No chemical bonding is involved.
• Therefore, such elements form a mixture.

Last verified on 12-04-2026

Explanation

• Group 17 elements are called halogens.
• They are highly reactive non-metals.
• These elements readily gain one electron.
• Chlorine is a member of Group 17.

Last verified on 12-04-2026

Explanation

• A mole is a unit used in chemistry.
• It represents a very large number of particles.
• This number is called Avogadro’s number.
• 1 mole contains 6.02 × 10²³ particles.
• These particles can be atoms, molecules, or ions.

Last verified on 12-04-2026

Explanation

• A new predator increases predation pressure on prey.
• This leads to a decrease in prey population.
• More prey get hunted and fewer survive.
• Ecosystem balance may temporarily change.
• So, prey population is most directly affected.

Last verified on 12-04-2026