Let’s Practise
1. Match the following:
| (a) Core | (iii) Innermost layer of the earth |
| (b) Minerals | (iv) Obtained from rocks |
| (c) Metals | (v) Obtained from ores |
| (d) Gemstones | (i) Used to make jewellery |
| (e) Coal | (ii) Used as fuel |
2. Answer in one word.
(a) It is used for making lubricants.
Answer: Petroleum
(b) Paraffin wax is obtained from it.
Answer: Petroleum
(c) It is used in the blast furnace of steel industries.
Answer: Coal
(d) These minerals do not contain metals in them.
Answer: Non-metallic
(e) This type of rock is made up of calcite.
Answer: Limestone
3. Fill in the blanks.
(a) Pumice rock is used by the dentist.
(b) Limestone is made of a mineral known as calcite.
(c) Marble is formed from metamorphosed limestone.
(d) Shale is made up of fine grains of clay and mud.
4. Write ‘T’ for True and ‘F’ for False.
(a) Fossil fuels are minerals. – T
(b) Granite is used in cutting tools. – F
(c) Igneous rocks are called fiery rocks. – T
(d) Basalt is made of calcite mineral. – F
5. Short answer questions
(a) How is coal formed?
Coal is formed from the remains of dead plants that got buried in the earth millions of years ago. Under high pressure and temperature, they decayed and turned into coal.
(b) What is an ore? Give one example.
An ore is a rock that contains metal in sufficient quantity to be extracted profitably.
Example: Haematite is an ore of iron.
(c) What is rock? List the different types of rocks with examples.
A rock is a naturally occurring solid composed of one or more minerals.
Types of rocks:
•Igneous rocks (e.g., Granite, Pumice)
•Sedimentary rocks (e.g., Sandstone, Limestone)
•Metamorphic rocks (e.g., Marble, Slate)
(d) What is a mineral? Name the two types of minerals with examples.
A mineral is a naturally occurring chemical substance found in rocks.
•Metallic minerals: Haematite, Bauxite
•Non-metallic minerals: Calcite, Gypsum
6. Long answer questions
(a) How are igneous, metamorphic and sedimentary rocks formed?
•Igneous rocks are formed by the cooling and solidification of magma or lava.
•Sedimentary rocks are formed from the deposition and cementation of sand, pebbles, and mud at the bottom of seas and oceans.
•Metamorphic rocks are formed when igneous or sedimentary rocks change under heat and pressure beneath the Earth’s surface.
(b) Write two uses of granite, slate, marble and quartzite.
•Granite: Used in statues/buildings, road paving
•Slate: Used in blackboards and tiles
•Marble: Used in buildings and sculptures
•Quartzite: Used in jewellery and glass industry
(c) Write five points about the conservation of coal and petroleum.
1.Use public transport or carpools.
2.Turn off car engines at traffic signals.
3.Switch off electrical appliances when not in use.
4.Use solar energy and energy-saving LED bulbs.
5.Use pressure cookers and biogas for cooking.
Critical Thinking
1. Give reasons for the following:
(a) Why should we use fossil fuels judiciously?
Because they take millions of years to form and are limited in supply. Overuse will lead to depletion.
(b) Why is igneous rock also called fiery rock?
Because it is formed from hot molten magma or lava that cools and solidifies.
2. Identify and write the name of the rock used to build this monument.
(a) Name of the rock: Marble
(b) Name the minerals found in this type of rock: Calcite
3. Write the ores of the following metals.
•Iron: Haematite
•Aluminium: Bauxite
•Copper: Copper pyrite
•Zinc: Sphalerite
Based on the picture showing molten lava flowing, here are the answers:
4. Look at the picture and answer the following questions:
(a) Which type of rock is formed due to this phenomenon?
→ Igneous rock
(b) Give few examples of the above mentioned rock type.
→ Granite, Pumice, Obsidian, Basalt
These rocks are formed when lava or magma cools and solidifies.