Answer;
They were used to make ammunition and explosives.
Materials such as scrap iron, rubber, and aluminum recycled during the war because they were used to make ammunition and explosives.
Step-by-step explanation;
During the world war recycling of materials such as scrap iron and aluminium was important because; metals were scarce during the war because they were needed to build ships, planes, tanks, bombs and gun parts.
People were encouraged to recycle used tin cans and the old rubber was collected and recycled for war efforts.