Which statement is true about AC

An air bubble of volume 20 cm³ is at the bottom of a lake 40 m deep, where the temperature is 4.0°c. the bubble rises to the surface, which is at a temperature of 20°c.take the temperature of the bubble’s air to be the same as that of the surrounding water. just as the bubble reaches the surface, what is its volume?

Electromagnetic induction. a coil of wire contains n turns and has an electrical resistance r. the radius of each turn is a. initially, inside the coil there exists a uniform magnetic field of magnitude b0 parallel to the axis of the coil. the magnetic field is then reduced slowly. the current induced in the coil is i. how long does it take for the magnitude of the uniform field to drop to zero?

According to the image below, which season is about to begin in the southern hemisphere? a. summer b. autumn c. winter d. spring