Work Done = Force x distance
Since she exerted a horizontal force of 20N over a distance of 5m, the work done is 20N x 5m which is equals to 100 joules
Magnesium oxide is an ionic compound that can be used as a building material. MO2 is actually a raw material that used in producing cement for building houses, buildings, and other constructions.
Many old structures were made of limestones. Limestone is from Calcium Carbonate (CaCO3) which is an ionic compound and can be used as a building material too.
A gas heated to millions of degrees would emit mostly x-rays.
Conservation and Rain Water Tank. Through conservation, they can save water in their own houses by lessening the use of water in an unimportant purpose; they can turn of the faucet when it is not used; they can use their laundry water to clean the bathroom and there are more. Through Rain Water Tank, they can create this structure in order to collect rain water and store it in the tank then use it afterwards such as in watering the plants.