Upon adding hydrochloric acid in copper oxide, it turns to blue-green color which is due to the formation of:

Which of the following imparts deep blue colour to glass?

Which metal is generally used for coating of brass utensils to prevent copper contamination?

Which one of the following metals does NOT react with cold water to liberate hydrogen gas?

Which one of the following is essential in corrosion of iron metal?

Which one of the following elements does not form solid hydrogen carbonate?