Explanation

Complete combustion of hydrocarbons (like methane, propane, etc.) in the presence of oxygen produces:

• Carbon dioxide (CO₂)
• Water (H₂O)

Therefore, the combustion products of hydrocarbons are carbon dioxide and water.

Explanation

The chemical formula for tetrafluoroethylene is C₂F₄.

Key points about Teflon:

Chemical name: Polytetrafluoroethylene (PTFE)

Monomer: Tetrafluoroethylene

Notable property: Highly non-stick surface, often used in cooking utensils

Explanation

An element with 7 valence electrons needs 1 more electron to complete its octet.

Therefore, its valency is 1, as it tends to gain 1 electron during bonding.

Explanation

Cobalt-60, an isotope of cobalt, is widely used in radiation therapy to treat cancer.

It emits gamma rays, which help destroy cancerous cells in medical treatments.

Explanation

The sentence gives advice or recommendation, which is best expressed using "should."

Correct sentence: Sonia should practice much if she wants to take part in the race.

Explanation

Promise: A commitment or assurance that one will do something or that something will happen.

The use of "shall" indicates a firm intention or vow about future support.

Explanation

Compassionate means showing kindness, care, and a desire to help others.

Sympathetic means showing understanding and care for someone else's suffering.

Compassionate means شفقت ، نگہداشت ، اور دوسروں کی مدد کرنے کی خواہش ظاہر کرنا

Sympathetic means کسی اور کی تکلیف کی تفہیم اور دیکھ بھال کرنا

Explanation

A polyprotic acid is an acid that can donate more than one proton (H⁺) per molecule.

1. H₃PO₄ (Phosphoric acid) → Triprotic acid (can donate 3 H⁺ ions)
2. HCN (Hydrocyanic acid) → Monoprotic (donates only 1 H⁺)
3. HCl (Hydrochloric acid) → Monoprotic

Explanation

To find the equilibrium constant (Kc) for the reaction H₂ (g) + I₂ (g) ⇌ 2HI (g), we use the formula:

Kc = [HI]² / [H₂] [I₂]

Given concentrations:

[HI] = 0.08 mol/dm³

[H₂] = 0.04 mol/dm³

[I₂] = 0.04 mol/dm³

Kc = (0.08)² / (0.04 × 0.04)

= 0.0064 / 0.0016

= 4

Explanation

1 atmosphere (atm) is a standard unit of pressure equal to 101.325 kPa, 760 mmHg, and 760 torr.

These units are used interchangeably in measuring atmospheric pressure.