Which statement is correct? a Star formation begins in the nebula
b White dwarfs become main-sequence stars when they gain mass
c Supergiants are stars that can absorb black holes
d Main-sequence stars are formed by comets

Aman tries to push a box of mass 4 kg with a force of 5 n but the box remains stationary if the coefficient of static friction is 0.45, what is the value of the maximum force of friction?

Photoelectrons with a maximum speed of 6.50 x 107 m/s are ejected from a surface in the presence of light with a frequency of 6.75 x 1014hz. if the mass of an electron is 9.10 x 10-31 kg, calculate in joules the maximum kinetic energy of a single electron. 3.84 x 10-15 j 1.92 x 10-15 j 5.92 x 10-23 j 3.07 x 10-16 j

What is the average speed of a car that travels 40mph for 1 hour and 60 mph in another hour will mark brainliest