Answer:
240 seconds
Explanation:
Data Given:
Distance Radio travel to earth = 7.19 ×10⁷ km
Speed of this radio signal = 3.00 ×10⁸ m/s
Solution:
First convert Km to m
1 km = 1000 m
7.19 ×10⁷ km = 7.19 ×10⁷ x 1000 = 7.19 × 10¹⁰m
Formula used to calculate time
Speed (S) = distance (d) / time (t)
rearrange above equation for time
time (t) = distance (d) / Speed (S) . . . . . . . . .(1)
Put values in equation 1
time (t) = 7.19 × 10¹⁰/ 3.00 ×10⁸ m/s
time (t) = 240 s
So 240 seconds it take for the signal to reach the earth
Use the formula triangle for quantitive chemistry
Answer:
The heat of vaporisation of methanol is "3.48 KJ/Mol"
Explanation:
The amount of heat energy required to convert or transform 1 gram of liquid to vapour is called heat of vaporisation
When 8.7 KJ of heat energy is required to vaporize 2.5 mol of liquid methanol.
Hence, for 1 mol of liquid methanol, amount of heat energy required to evaporate the methanol is = 
= 3.48 KJ
So, the heat of vaporization 
Therefore, the heat of vaporization of methanol is 3.48KJ/Mol