25-minute Test : Part II Microscopic World I

• A. It has 19 neutrons.
• B. It has 20 protons.
• C. X is found in Group I of the Periodic Table.

• D. X is a non-metal.

The following table shows the atomic numbers and mass numbers of elements X and Y respectively. X reacts with Y to form compound Z. The formula mass of Z is close to

• A. 21.
• B. 30.
• C. 43.
• D. 62.

Which of the following statements about lithium is INCORRECT?

• A. It is malleable and ductile.
• B. It conducts electricity by mobile ions.
• C. Lithium ions pack closely together in a regular pattern in the solid state.
• D. Metallic bonds exist between lithium ions and delocalized electrons.

An atom of element P has 10 neutrons and 9 electrons.

The following table shows the number of neutrons and the number of electrons of four ions W⁻, X⁺, Y²⁻ and Z²⁺.

Which of the following atoms is an isotope of P?

• A. W

• B. X

• C. Y

• D. Z

• A. protons.
• B. neutrons.
• C. electron shells.
• D. outermost shell electrons.

Which of the following ions does NOT contain dative covalent bond?

• A. BF₄⁻
• B. CO₃²⁻
• C. NH₄⁺
• D. H₃O⁺

Which of the following statements concerning the reactivity of elements is correct?

• A. Cl is less reactive than F.
• B. Na is less reactive than Li.
• C. Ar is more reactive than Al.
• D. Ca is more reactive than K.

The set-up of an experiment is shown in the following diagram. What can be observed after the circuit is closed for a period of time?

• A. A blue patch migrates towards electrode X.

• B. A yellow patch migrates towards electrode X.

• C. A purple patch migrates towards electrode Y.

• D. An orange patch migrates towards electrode Y.

Which of the following is the correct explanation for the low melting point of fluorine?

• A. There is only one bond pair of electrons in each fluorine molecule.
• B. The atoms in each fluorine molecule are bonded together by weak covalent bond.
• C. There are only two fluorine atoms in each fluorine molecule.
• D. Fluorine molecules are held together by weak van der Waals’ forces.

The following table shows some physical properties of four substances P to S. Which of these substances is likely to be an ionic compound?

• A. P

• B. Q

• C. R

• D. S