Adaptive Practice
Some Basic Concepts of Chemistry
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⏱ 0:30
Easy
What is the SI unit of amount of substance?
Easy
Avogadro's number is approximately equal to:
Easy
If 1 mole of oxygen gas (O₂) has a mass of 32 g, what is the mass of 0.5 mole of oxygen gas?
Medium
Which of the following represents the correct relationship between molarity (M), molality (m), and density (d) of a solution?
Medium
Calculate the number of molecules in 18 g of water (H₂O). (Atomic masses: H=1, O=16)
Medium
Which of the following is NOT a postulate of Dalton's atomic theory?
Easy
A gas occupies 22.4 L at STP. How many moles of gas are present?
Medium
Which of the following statements about molar volume is correct?
Hard
The empirical formula of a compound is CH₂. If its molecular mass is 56 g/mol, what is its molecular formula? (Atomic masses: C=12, H=1)
Easy
Which concept explains that the mass of reactants equals the mass of products in a chemical reaction?