(i) A pressure of 15 Pa is exerted on an object with a surface area of 3m2. Calculate the force acting on the area.(ii) Why should we lubricate parts of our machines regularly?(iii) Why do astronauts use radio signals to communicate in space?(iv) Why are plastics considered as environmental hazard?(v) What is alloy? Why they are made?(vi) Name any three products obtained from crude oil.(vii) What are the uses of microorganisms in our life?(viii) What are the differences between zoological park and botanical park?​