लकड़ी में एक अनुदैर्ध्य दरार जो आमतौर पर वार्षिक वलयों के लंबवत होती है, उसे क्या कहा जाता है?

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?