Test – Form 2 – Second Term Holiday

When a purple crystal is dropped into water, two things happen: the crystal dissolves (breaks apart) in the water, and then the purple particles spread out through the water by diffusing. There is no chemical reaction happening – the crystal is just mixing with water. So dissolving and diffusing both happen, which is option D.

Copper is a metallic element (shiny metal), sulfur is a non-metallic element (yellow powder), brass is a mixture (copper mixed with zinc), and methane is a compound (carbon and hydrogen joined together). Option C gets all of these correct.

Electrons have a negative charge (-1) and are very light compared to protons and neutrons. Their mass is about 1/2000 of a proton’s mass. So the charge is -1 and the mass is 1/2000.

Isotopes are atoms that have the same number of protons but different numbers of neutrons. W has 2 protons and Y has 2 protons, so they are the same element. W has 2 neutrons and Y has 3 neutrons, so they are isotopes of each other.

Ionic compounds conduct electricity well when dissolved or melted (because the ions can move), and they have high melting points (because the ionic bonds are strong). Row B shows good electrical conductivity and a high melting point of 3652°C.

In methane, covalent bonds form when atoms share pairs of electrons. Both carbon and hydrogen atoms end up with the same number of electrons in their outer shell as a noble gas (which makes them stable). This is what row B describes.

Neutralization is when an acid reacts with a base to make salt and water. Nitric acid (HNO₃) + Sodium hydroxide (NaOH) → Sodium nitrate (NaNO₃) + Water (H₂O). The equation must be balanced and show the correct state symbols.

As you go across a period from left to right, elements become less metallic. Statement 2 is correct: beryllium is more metallic than carbon. Statement 4 is correct: magnesium is more metallic than silicon. Statements 1 and 3 are wrong because they say the opposite.

As you go down Group 1 (alkali metals like lithium, sodium, potassium), the melting point decreases (they get easier to melt), density decreases (they get lighter), and reactivity increases (they react more violently with water). Row A shows this correct pattern.

Chlorine and bromine are both halogens (Group 7 elements), so they both react with aqueous potassium iodide. However, chlorine is more reactive than bromine because it’s higher up in Group 7. The higher you go in Group 7, the more reactive the element becomes.

Transition elements (like iron, copper, nickel) are metals that have high densities (they are heavy for their size) and high melting points (they need lots of heat to melt). This is because they have strong metallic bonding.

Noble gases have full outer shells of electrons, which makes them very stable. Looking at the diagrams, option C shows an atom with a complete outer shell (8 electrons in the outer shell), which is typical of noble gases like neon or argon.

When a metal reacts with an acid, it produces a salt and hydrogen gas. The reaction is: Zinc + Hydrochloric acid → Zinc chloride + Hydrogen gas. You can test for hydrogen by putting a lit splint near it – it will make a squeaky pop sound.

Aluminium is used in aircraft because it’s strong but very light (low density). This means planes can be strong enough to fly safely but not too heavy. Iron and copper are much heavier, and potassium is too reactive and soft.

The diagram shows particles arranged in a regular pattern with layers. This structure matches both brass (an alloy with atoms arranged in layers) and graphite (carbon atoms arranged in layers that can slide over each other). Sodium chloride has a different cubic structure, not this layered arrangement.