Question 

Diamond is one form of carbon. 

(a) (i) State the name of another form of carbon.

▶️Answer/Explanation

Answer: Graphite

(ii) Diamond is used in cutting tools such as those shown in Fig. 11.1.

State why diamond is used.

▶️Answer/Explanation

Answer: Diamond is hard.

(b) Silicon dioxide, SiO₂, has a similar structure to diamond. 

Fig. 11.2 shows the structure of silicon dioxide.

Describe the structure and bonding in silicon dioxide.

▶️Answer/Explanation

Answer: Silicon dioxide has a giant covalent structure where each silicon atom is covalently bonded to four oxygen atoms, and each oxygen atom is bonded to two silicon atoms. This creates a strong, rigid lattice structure.

(c) One of the isotopes of carbon is called carbon-12 and the other is called carbon-14. 

Table 11.1 shows some information about carbon-12.

Complete the table for carbon-14.

	number of protons	number of neutrons	number of electrons
carbon-12	6	6	6
carbon-14

▶️Answer/Explanation

Answer: Carbon-14 has 6 protons, 8 neutrons, and 6 electrons.

(d) Relative atomic mass, A_r, is defined in terms of a carbon atom.

Complete the definition of relative atomic mass.

Choose words from the list. Each word may be used once, more than once or not at all.

average      compound      density      element      formula      mass

Relative atomic mass is the …… mass of naturally occurring atoms of an …… on a scale where the ¹²C atom has a …… of exactly 12 units.

▶️Answer/Explanation

Answer: Relative atomic mass is the average mass of naturally occurring atoms of an element on a scale where the ¹²C atom has a mass of exactly 12 units.

(e) Calculate the number of moles in 0.6 g of carbon.

[A_r : C, 12;]

▶️Answer/Explanation

(moles = 0.6 ÷ 12 =) 0.05 ;