Metal X is in Group II of the Periodic Table.
X is reacted separately with dilute sulfuric acid and with oxygen.
Which row identifies the products of each reaction?
| products with dilute sulfuric acid | product with oxygen | |
|---|---|---|
| A | XSO4 and H2 | XO |
| B | XSO4 and H2 | XO2 |
| C | X2SO4 and H2 | XO |
| D | X2SO4 and H2 | XO2 |
▶️ Answer/Explanation
Ans: A
For Group II metals:
- With dilute sulfuric acid:
- The general reaction is: X + H2SO4 → XSO4 + H2
- This produces a sulfate salt (XSO4) and hydrogen gas (H2)
- The formula X2SO4 would be incorrect as Group II metals have a +2 charge
- With oxygen:
- Group II metals form oxides (XO) when reacting with oxygen, not peroxides (XO2)
- The reaction is: 2X + O2 → 2XO
Therefore, option A correctly shows both reactions for a Group II metal.
Rubidium is an element in Group I of the Periodic Table.
Which row describes a physical property and a chemical property of rubidium?
| physical property | chemical property | |
|---|---|---|
| A | hard | reacts with water |
| B | hard | does not react with water |
| C | soft | reacts with water |
| D | soft | does not react with water |
▶️ Answer/Explanation
Ans: C
Rubidium is an alkali metal in Group I with these properties:
Physical property: Like all Group I metals, rubidium is soft (can be cut with a knife).
Chemical property: All Group I metals react vigorously with water, producing hydrogen gas and an alkaline solution.
Therefore, the correct description is option C: soft (physical) and reacts with water (chemical).
J, L and M are elements in the Periodic Table.
- J has the highest density.
- L has the highest reactivity with water.
- M has the highest atomic number.
Which row identifies the elements J, L and M?
| J | L | M | |
|---|---|---|---|
| A | copper | lithium | bromine |
| B | lithium | copper | bromine |
| C | bromine | copper | lithium |
| D | copper | bromine | lithium |
▶️ Answer/Explanation
Ans: A
Let’s analyze each characteristic:
1. Highest density (J): Copper (8.96 g/cm³) has higher density than lithium (0.534 g/cm³) and bromine (3.12 g/cm³).
2. Highest reactivity with water (L): Lithium (Group I metal) is much more reactive with water than copper (which doesn’t react with water) or bromine (a halogen).
3. Highest atomic number (M): Bromine (35) has higher atomic number than copper (29) and lithium (3).
Therefore, the correct identification is:
J = copper, L = lithium, M = bromine → Option A.
Which statement about elements in Group I of the Periodic Table is correct?
A) Rubidium has a greater density than caesium.
B) Lithium has a higher melting point than potassium.
C) Potassium is more reactive than rubidium.
D) Rubidium atoms have more outer shell electrons than sodium atoms.
▶️ Answer/Explanation
Ans: B
Let’s evaluate each statement:
A) Incorrect – Density increases down Group I, so caesium has greater density than rubidium.
B) Correct – Melting points decrease down Group I. Lithium (180°C) has higher melting point than potassium (63°C).
C) Incorrect – Reactivity increases down Group I, so rubidium is more reactive than potassium.
D) Incorrect – All Group I elements have 1 outer shell electron, regardless of their position in the group.