Questions

Fog is tiny water droplets or ice crystals suspended in the air at or near the Earth's surface. Hence, fog is an example of a colloidal system liquid dispersed in gas.

Add together values in corresponding positions of the top two crosses, and put the result in the lower left cross.

Calculate the difference between values in corresponding positions of the top two crosses, and put the result in the lower right cross.

Finally add together the values in corresponding positions of the lower two crosses to give the values in the central cross

The one word substitute for 'a drawing on transparent paper' is Transparency.

Saw dust contains carbon which is oxidised to carbon  dioxide by concentrated nitric acid;