According to IS 1077 : 1992, for common burnt clay building bricks of 'class 25', the water absorption after 24 hours of immersion shall NOT be more than how many per cent by weight?

Which of the following artificial stones is produced by moulding a mixture of iron slag and Portland cement?

Enamel paint is generally prepared by adding:

Dorry's testing machine is used for which test on building stones?