1. How many atoms are present in 0.500 mol of NH3?

A. 1.20 ×1023

B. 3.01 ×1023

C. 6.02 ×1023

D. 1.20 ×1024

2. The structural formula of a dioxin is shown below.

What is its empirical formula?

A. C6O

B. C6H4O

C. C6H6O

D. C12H8O2

3. 100.0 cm3 of a 0.50 mol dm–3 solution of BaCl2 is added to 50.0 cm3 of a 0.10 mol dm–3 solution of Na2SO4. A precipitate of BaSO4 is formed according to the equation below.

BaCl2 (aq) + Na2SO(aq)→BaSO4(s) + 2NaCl (aq)

What is the amount, in mol, of BaSO4 produced?

A. 0.0050

B. 0.010

C. 0.050

D. 0.10

4. Which volumes of gases at standard temperature and pressure have the same mass as 100 cm3 of O2?

  • I. 50 cm3 of SO2
  • II. 100 cm3 of CH4
  • III. 100 cm3 of SiH4

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

5. The diagram represents the emission spectrum of hydrogen. Groups of arrows are labelled W, X and Y.

Which statement is correct?

A. The arrows represent the transition of electrons to different energy levels when heat is supplied.

B. The arrows of W represent emission in the UV region.

C. The smallest arrow of X represents a violet line in the emission spectrum.

D. The arrows of Y represent emission of electromagnetic waves with higher energy than those represented by X and W.

6. Which species have the same electron arrangements?

I. O2–, F, Ne

II. Li+, Na+, K+

III. S2–, Ar, K+

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

7. Which statement about the periodic table is correct?

A. The elements with atomic numbers 8, 16 and 34 have the same number of main energy levels.

B. The elements with atomic numbers 8, 9 and 10 have similar chemical properties.

C. The elements with atomic numbers 20, 21 and 22 are in the same group.

D. The elements with atomic numbers 20, 38 and 56 have the same number of electrons in their outer energy level.

8. The horizontal axis of the bar chart represents the elements of period 3 from sodium to chlorine (excluding silicon). What could the vertical axis represent?

A. Melting point of the element

B. Electronegativity of the bonded atom

C. Ionic radius of the most common ion

D. First ionization energy in the gaseous state

9. The electronegativities of four elements are given in the table.

Which statement is correct?

A. W and X form an ionic compound.

B. W and X form a covalent compound.

C. Y and Z form an ionic compound.

D. Y and Z form a covalent compound.

10. Which combination of length and strength of the carbon‒to‒carbon bonds in C2H2 and C2H4 is correct?




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