Chapter 8 : Manufactured Substances in Industry

Substance X conducts electricity in the solid state and also in the molten state. Substance X is

• an alloy

• a salt

• a fat

• a metal oxide

The diagram shows the arrangement of atom in brass. Why is brass harder than pure copper?

• Zinc atoms form very strong hydrogen bonds with copper atoms.

• Zinc atoms prevent the layers of copper atoms from sliding over each other.

• Zinc atoms prevent electrons from moving freely in the sea of electrons.

• Zinc atom contributes more electrons to the sea of electrons.

The main substance in the making of all types of glass is

• calcium carbonate

• sodium carbonate

• lead(II) oxide

• silicon dioxide

The making of ceramic objects involves the heating of the object at a high temperature in a furnace. Why is this process carried out?

• To remove water

• To keep its shape

• To break all chemical bonds

• To form strong covalent bonds and ionic bonds

Silicon carbide, SiC, is an example of advanced ceramic which can be used to make

• car brakes

• window panes

• electrical cables

• water tanks

What properties are involved in the making of car bumpers?

i. Light

ii. Electrical insulator

iii. Easy to mould

iv. Heat resistant

• i and ii

• i and iii

• ii and iv

• iii and iv

Industrial Revolution 4.0 (IR 4.0) will witness the Internet of Things (IOT) in almost all aspects of daily lives. All electronic devices can be connected to the Internet via computer networks. What material is most suitable to make the cables?

• Aluminium

• Copper

• Optical cables

• Fibre glass

A conducting material loses its electrical resistance below a certain temperature called the

• melting temperature

• boiling temperature

• critical temperature

• zero temperature

Which of the following is the chemical reaction that occurs when photochromic glass darkens?

• AgCl ⟶ Ag⁺ + Cl^-

• Ag⁺ + e^- ⟶ Ag

• Clˉ + UV ⟶ Cl

• Cl + e^- ⟶ Clˉ

Which of the following is correct about the properties of soda-lime glass and borosilicate glass?

• Soda-lime glass has a low density and a high melting point, whereas borosilicate glass has a high density and a low melting point.

• Soda-lime glass has a low density and a low expansion coefficient, whereas borosilicate glass has a high density and a high expansion coefficient.

• Soda-lime glass has a high melting point and a low thermal shock resistance, whereas borosilicate glass has a low melting point and a high thermal shock resistance.

• Soda-lime glass has a low expansion coefficient and a low thermal shock resistance, whereas borosilicate glass has a high expansion coefficient and a high thermal shock resistance.