Answer:
True
Explanation:
When a star has reached the main sequence stage, hydrogen is converted into helium by nuclear fusion, . Also, the gravity and pressure are balanced because the star does not radiate more heat than it generates. A star usually spends most of its lifetime at this stage.
The Zero Age Main Sequence is the period during the main sequence when a star stops contracting, and begin to fuse hydrogen in its core.
Answer:
b. 9.5°C
Explanation:
= Mass of ice = 50 g
= Initial temperature of water and Aluminum = 30°C
= Latent heat of fusion = 
= Mass of water = 200 g
= Specific heat of water = 4186 J/kg⋅°C
= Mass of Aluminum = 80 g
= Specific heat of Aluminum = 900 J/kg⋅°C
The equation of the system's heat exchange is given by

The final equilibrium temperature is 9.50022°C
Answer:
It can be said to be reliable although it is not valid
Explanation:
This is because Reliability means an indicator of consistency, A measure should produce similar or the same results consistently if it measures the same quantity. So does the thermometer measures over 5days but it is not valid because it deviates from the real value
Answer:
the pressure at the depth is 1.08 ×
Pa
Explanation:
The pressure at the depth is given by,
P = h
g
Where, P = pressure at the depth
h = depth of the Pacific Ocean in the Mariana Trench = 36,198 ft = 11033.15 meter
= density of water = 1000 
g = acceleration due to gravity ≈ 9.8 
P = 11033.15 × 9.8 × 1000
P = 1.08 ×
Pa
Thus, the pressure at the depth is 1.08 ×
Pa