25-minute Test : Part XII Patterns in the Chemical World

Which of the following nitrate solutions is/are coloured?

(1) Zn(NO₃)₂(aq)

(2) Ti(NO₃)₃(aq)

(3) Sc(NO₃)₃(aq)

• A. (1) only
• B. (2) only
• C. (1) and (3) only
• D. (2) and (3) only

Which oxides, when added to water, would form a solution with the highest pH?

• A. Na₂O
• B. MgO
• C. Al₂O₃
• D. SiO₂

Which of the combinations concerning the solution formed when the oxide dissolves in water are correct?

• A. (1) and (2) only
• B. (1) and (3) only
• C. (2) and (3) only
• D. (1), (2) and (3)

Which of the following pairs of Period 2 elements has the smallest difference in melting point?

• A. Li and O
• B. Be and O
• C. B and F
• D. C (diamond) and F

Which of the following statements concerning the melting points of Period 3 elements is INCORRECT?

• A. Magnesium has a higher melting point than sodium because magnesium atoms have more outermost shell electrons, which allows them to form stronger metallic bonds.
• B. Sulphur has a higher melting point than phosphorus because sulphur has a larger molecular size, and the van der Waals’ forces between sulphur molecules are stronger.
• C. Silicon has the highest melting point because its molecules are held together by strong covalent bonds throughout the structure.
• D. Argon has the lowest melting point because it is monoatomic and the van der Waals’ forces between its molecules are the weakest.

Which of the following statements concerning the oxides of Period 3 elements from Na to Cl are correct?

(1) The oxides change from basic to amphoteric, and eventually to acidic.

(2) The bonding of the oxides changes from ionic to covalent.

(3) The melting points of the oxides decrease gradually.

• A. (1) and (2) only
• B. (1) and (3) only
• C. (2) and (3) only
• D. (1), (2) and (3)

The atoms of an element with a strong metallic character have a high tendency to lose its outermost shell electrons to form positive ions. Which of the following statements concerning the metallic character of elements is INCORRECT?

• A. The metallic character of elements generally decreases across a period.
• B. The metallic character of elements generally increases down a group.
• C. The stronger the metallic character of an element, the stronger the metallic bonding it can form between its constituent particles.
• D. The stronger the metallic character of an element, the smaller is its electronegativity.

What variation in physical properties of Period 3 elements does the graph (NOT drawn to scale) sketch?

• A. Melting point
• B. Atomic size
• C. Electronegativity
• D. Electrical conductivity

The diagram shows two different molecular structures of phosphorus. White phosphorus exists as simple molecules, and red phosphorus exists as polymeric chains. Which of the following statements concerning these two kinds of phosphorus are correct?

(1) The melting point of red phosphorus is higher than that of white phosphorus.

(2) They both have the same relative molecular mass.

(3) White phosphorus is more reactive than red phosphorus.

• A. (1) and (2) only
• B. (1) and (3) only
• C. (2) and (3) only
• D. (1), (2) and (3)

The graph (NOT drawn to scale) shows the variation of the melting points of elements in Periods 2 and 3 of the Periodic Table. Which of the following pairs of elements both can form oxides that can react with 0.1 M of HCl(aq)?

• A. V and W

• B. X and Y

• C. W and X

• D. W and Z