Which is the correct set of carbonate ores?
$(a)$ Magnesite $(b)$ Siderite $(c)$ Zincite $(d)$ Argentite

"Metals are usually not found as nitrates in their ores."
Out of the following two $(a)$ and $(b)$ reasons,which is/are true for the above observation?
$(a)$ Metal nitrates are highly unstable.
$(b)$ Metal nitrates are highly soluble in water.

Bronze is a mixture of which metals?

Which mineral was used in the isolation of radium?

Which of the following statements is incorrect?

Which is not a halide ore?