How many hydrogen atoms are in a molecule of the following compound: Hydrochloric acid HCl

Hydrogen atom is represented by the symbol H . A chemical formula is a symbolic representation of the compounds, which shows atoms of the elements and the number of atoms present in that particular molecule of the compound. A molecule of hydrochloric acid contains one hydrogen atom and one chlorine atom.

Some air is pumped into a bicycle tyre. Predict what will happen to the amount of gas pressure inside the tyre as air is pumped in. Use particle theory to explain your prediction.

Gas pressure is the effect of the forces caused by the collisions from gas particles on the walls of a container. When air is pumped into a bicycle tyre, the amount of gas inside the tyre will increase and will exert some pressure inside the wall of the tyre. This will increase the gas pressure inside the tyre. The particles in a gas are far apart and moving around. They collide with each other and the sides of the container they are in. This is called Brownian motion. This collision causes pressure on the walls. When the gas is filled in the tyre the moving gas particles exert pressure inside the tyre which increases the gas pressure and results in the inflation of the tyre.

E M B I B E

Cambridge Lower Secondary Science Stage 8 : Student's book>Chapter 4 - Elements, Compounds and Mixtures>End of chapter review>Q 6

EASY

Lower Secondary Stage 8

IMPORTANT

Earn 100

How many hydrogen atoms are there in a molecule of the following compound:

Methane $({CH}_{4})$

Important Questions on Elements, Compounds and Mixtures

EASY

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Student's book>Chapter 4 - Elements, Compounds and Mixtures>End of chapter review>Q 6

How many hydrogen atoms are in a molecule of the following compound:

Hydrochloric acid $(HCl)$

EASY

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Student's book>Chapter 4 - Elements, Compounds and Mixtures>End of chapter review>Q 7

Which one of these is an element?

EASY

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Student's book>Chapter 4 - Elements, Compounds and Mixtures>End of chapter review>Q 8

Copper is a shiny metal. A piece of it is heated in oxygen. Its surface becomes dull and black. Name the compound that is made in this chemical change.

MEDIUM

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Student's book>Chapter 4 - Elements, Compounds and Mixtures>End of chapter review>Q 8

Copper is a shiny metal. A piece of it is heated in oxygen. Its surface becomes dull and black. Describe how the compound is different from copper.

EASY

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Student's book>Chapter 4 - Elements, Compounds and Mixtures>End of chapter review>Q 9

A chemical reaction between hydrochloric acid and magnesium produces magnesium chloride

({MgCI}_{2})

. Is magnesium chloride an element, compound or mixture?

MEDIUM

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Student's book>Chapter 4 - Elements, Compounds and Mixtures>End of chapter review>Q 10

Some air is pumped into a bicycle tyre.

Predict what will happen to the amount of gas pressure inside the tyre as air is pumped in.
Use particle theory to explain your prediction.

MEDIUM

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Student's book>Chapter 4 - Elements, Compounds and Mixtures>End of chapter review>Q 11

Use particle theory to explain why you can compress a gas but not a liquid.

MEDIUM

Lower Secondary Stage 8

IMPORTANT

Cambridge Lower Secondary Science Stage 8 : Student's book>Chapter 4 - Elements, Compounds and Mixtures>End of chapter review>Q 12

Rock salt is found in the ground. It is a mixture of rock particles and salt. Describe how you would produce pure, dry salt from rock salt. You should explain the function of each step.