consider the substances below.
• 1 mol of beryllium
• 1 mol of salt
• 1 mol of water
• 1 mol of hydrogen
which statement is true about these substances? 1) they have exactly the same mass.2) they have different numbers of particles.3) they have the same number of atoms.4) they have different masses.

Answer : The correct option is, 4) They have different masses.

Explanation :

1) They have exactly the same mass.

This statement is incorrect, because of the different molar mass of the substance. As the molar mass of the substance is different. That means their mass will also different.

2) They have different numbers of particles.

This statement is incorrect, because every substance contains same number of particles not different numbers of particles. That means 1  mole of substance contains number of particles.

3) They have the same number of atoms.

This statement is incorrect, because every substance have the different number of atoms.

As, beryllium has 1 number of atoms. So, 1 mole of beryllium contains number of atoms.

As, water has 3 number of atoms. So, 1 mole of water contains number of atoms.

4) They have different masses.

This statement is correct, because of the different molar mass of the substance. As the molar mass of the substance is different. That means their mass will also different.

Hence, the correct option is, 4) They have different masses.