निम्नलिखित में से किस भवन निर्माण पत्थर में अधिकतम अग्नि-प्रतिरोधी (fire-resisting) गुण होता 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?