Answer:
Explanation: n=m/M(molar mass)
n=24.3 grams/(16+2x1.008)grams/moles(molar mass of H2O)
n=24.3grams/18.016grams/moles
n=1.35moles
Time taken for star to reach Earth = 7.5 years
<h3>Further explanation</h3>
Given
7.5 light years(distance Earth-star)
Required
Time taken
Solution
Speed of light=v = 3 x 10⁸ m/s
1 light years = 9.461 × 10¹⁵ m= distance(d)
So time taken for 1 light years :
time(t) = distance(d) : speed(v)
t = 9.461 × 10¹⁵ m : 3 x 10⁸ m/s
t = 3.154 x 10⁷ s = 1 years
So for 7.5 light years, time taken = 7.5 years
The beaker of acetic acid will cool more quickly.
The specific heat capacity of acetic acid is about half that of water.
Thus, it takes twice as much heat gain (or loss) in acetic acid to cause a given change in temperature.
If everything else is constant and heat is being lost at the same rate, the temperature of the acetic acid should drop twice as fast as that of water.
Mass 456
relative mass 82
moles
mass = rm x moles
456/82 = 5.5609756....
