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 standard temperature and pressure conditions enthalpy is usually measured under are 1kPa and 273K (option A).
<h3>What is enthalpy?</h3>
Enthalpy in thermodynamics is a measure of the heat content of a chemical or physical system.
Enthalpy is the sum of the internal energy and pressure times volume It can be calculated using the following formula:
H = E + P V
Where;
H = Enthalpy
E = internal energy
P = pressure
V = volume
However, the enthalpy of a substance is usually measured under standard temperature and pressure.
- The standard temperature is 273 Kelvin or K
- The standard pressure is 1kPa
Learn more about enthalpy at: brainly.com/question/13996238
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