Answer:One Astronomical Unit is the distance between the Earth and the Sun, this acts as a sort of a cosmic metre stick. Astronomers don't and cannot measure distances. Distances are merely inferred from what actually has been measured, such as an angle, a relative luminosity, a time period
Explanation:
Solution,
Mass of Mg - 21gm
molar mass of Mg - 24gm
moles = Given mass/ Molar mass
moles = 21/24 = 0.875
1 mole of Mg produce 1 mole of H2 gas
so 0.875 mole of Mg will produce 0.875 moles of H2 gas
One mole of H2 gas = 22.4 litre
0.875 mole of H2 gas = 0.875×22.4
0.875 mole of H2 gas = 19.60 litre
So the nearest ANSWER is Option four 19.37 litre.
the nucleus of an atom is held together by the strong force, while the electrons are held in the atom by the electric force.
