Answer:
8.31 × 10⁻²² kJ
Explanation:
Step 1: Given data
Energy required to remove one mole of electrons from the atoms at the surface of a solid metal: 500 kJ/mol e⁻
Step 2: Calculate how much energy does it take to remove a single electron from an atom at the surface of this solid metal
We will use Avogadro's number: there are 6.02 × 10²³ electrons in 1 mole of electrons.
500 kJ/mol e⁻ × 1 mol e⁻/6.02 × 10²³ e⁻ = 8.31 × 10⁻²² kJ/e⁻
Answer: The given quantity is 2 moles of magnesium or 48 g of magnesium.
The unknown quantity is mass of MgO in grams.
Molar mass of MgO = 40 g
Explanation: 
As can be seen from the chemical equation, 2 moles of magnesium react with 1 mole of oxygen gas to give 2 moles of MgO.
According to mole concept, 1 mole of every substance weighs equal to its molar mass.
Thus 
of magnesium produce=
of MgO.
Molar mass is the mass in grams of 1 mole of the substance.
Thus if 2 moles of MgO weigh= 80 g
1 mole of MgO will weigh=
Thus molar mass of MgO is 40 g.
Pressure what causes the molecules and matter to change .
Answer:
Periods
Explanation:
The vertical columns on the periodic table are called groups or families because of their similar chemical behavior. All the members of a family of elements have the same number of valence electrons and similar chemical properties. The horizontal rows on the periodic table are called periods.
