Which of the following is a compound?

Which gas is used in balloons and is also an element?

Which of the following is not an element?

What is the chemical formula of carbon dioxide?

Which of these is a mixture and not a compound?

Which metal is liquid at room temperature?

Which element is essential for making bones strong?

Which of the following is a compound found in the human body?

What does NaCl stand for?

Which of the following elements is used in making light bulbs?