The reaction is actually endothermic because delta H is positive, indicating that it absorbing heat.
Answer: Option (4) is the correct answer.
Explanation:
It is known that density is mass divided by volume.
Mathematically, Density = 
Since, density is directly proportional to mass. So, more is the mass of an element more will be its density.
Mass of magnesium is 24.305 g/mol.
Mass of barium is 137.327 g/mol.
Mass of beryllium is 9.012 g/mol
Mass of radium is 226 g/mol.
Hence, radium has more mass therefore it will have the greatest density at STP.
This is false. The amount of electrons in lithium (Li) is not 7, it is 3. There are 3 electrons in lithium.
Answer:
the amount of matter it contain