Question

If gas is passed longer than required, the bond becomes ____________

(a) Impaired

(b) Stronger

(c) Weaker

(d) Does not affect much

The question was posed to me in an online interview.

My doubt stems from Carbon Dioxide Mould topic in portion Moulding Machines & Special Moulding Processes of Foundry and Forging

Answer 1

The correct choice is (a) Impaired

Easy explanation: When the gas is passed at the required pressure, the compression strength of a given sand mixture reaches its maximum at some critical amount of gas passed. If gassing is continued beyond the critical point, the strength of the bond is impaired.