I'm going to answer this by using rounded numbers for the atomic masses. You need only go back and put the numbers in from your periodic table. My answers will be close, but not what you should get.
Find the Molar Mass of MgCl2
Mg = 24 grams
2Cl = 2 * 35.5 = 71 grams
Total = 95 grams
Find the mols in 339 grams
1 mole = 95 grams
x mol = 339
Solve
339 = 95x Divide by 95
339/95 = x
x = 3.67 mols Answer
Answer:
5. Is greater than mg, always
Explanation:
If the cone has an inclination of angle β, the sum of forces will be:
x-axis (centripetal axis):
N*sin β = m*ax where ax is the centripetal acceleration
y-axis:
N*cos β - m*g = m*ay where ay is the vertical acceleration. If the block starts falling down, ay will be negative. If the block starts sliding up, ay will be positive. If the block does not move up nor down, ay=0.
Solving for N:

If ay is positive or zero, N will be greater than mg. If ay is negative, N will be less than mg.
If the block is sliding along a horizontal circular path (not up, nor down), ay = 0, so N will always be greater than mg.
Explanation:
q= n e
6 × 10^-11 = n (1.6 × 10^-19)
n = 6×10^-11 / 1.6 × 10^-19
n= 3.75 × 10⁸ electrons
Answer:
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Explanation: