The length of day and night varies throughout the year because the equator is tilted 23.5 degrees from the Earth's orbit.
The Earth revolves around the Sun. It is tilted vertically at an angle of 23.5° on its circumambulation route, half of the year when it is summer the northern part is inclined towards the sun.
The second half of the time when it is cold, the Earth is away from the Sun.
Changes in the tilt of the earth can affect the intensity of the weather more tilt means more heat and less cold; Less tilt means less heat and more cold.
Important Point
The axle of the earth is not perpendicular to its orbit. Hence statement 1 is correct.
The length of day and night varies throughout the year because the equator is tilted 66.5 degrees from the Earth's orbit. Hence statement 2 is incorrect.
If the earth was not inclined, we would not have experienced the weather. Changes in the tilt of the earth can affect the intensity of the weather. Hence statement 3 is correct.