PLEASE HELP QUICK The Doppler Effect is noticed in which of the following situations?

a. When a car with its honking horn moves towards you and then drives away.

b. When birds fly in formation, and the goose at the front is honking.

c. When a drum is struck hard.

d. When sound does not travel in a vacuum.

The valence of aluminum is +3, and the valence of the chlorine is -1. the formula fir the aluminum chloride is correctly written as

Imagine one batch of soup (batch “a”) is made with 8.19 g/can of salt, according to the recipe, and a second batch of soup (batch “b”) is made with 8.32 g/can of salt. explain which batch would be more resistant to frost damage if it is shipped a great distance in winter and explain why.

What is the typical rotational frequency frot for a molecule like n2 at room temperature (25∘c)? assume that d for this molecule is 1å=10−10m. take the total mass of an n2 molecule to be mn2=4.65×10−26kg. you will need to account for rotations around two axes (not just one) to find the correct frequency. express frot numerically in hertz, to three significant figures.