What answer is this? Pls help I’m freaking out

Wavelength,frequency,and energy are related.what happens to a wave as it’s wavelength gets shorter?

Which of the following changes will result in a stronger electromagnet? a. using fewer coils of wire b. using a higher voltage c. using a shorter nail d. using a longer wire

An object weigh 40n in air ,weigh 20n when submerged in water,and 30n when submerged in a liquid of unknown liquid density.what is the density of unknown of liquid?