In the united states, the main federal agency for the promotion of public health and welfare is the: department of health and human services centers for disease control and prevention national institutes of health food and drug administration

Department of Health and Human Services

Explanation:

The Department of Health and Human Services (HHS) is the main federal agency for the promotion of public health and welfare. This is a cabinet-level department of the U.S. government. It was called the Department of Health, Education, and Welfare (HEW) in the past. This agency is responsible for protecting the health of Americans as well as providing essential human services.

1 - wave length

2 - amplitude

3 - crest

4 - trough

explanation:

duh.

answer: 2×10^-2kg

explanation: density= mass per volume

vol=mass/density

converting to s.i units we have;

3÷1000kg = 0.003

1.5÷100m = 0.15

0.003/0.15 = 0.02kg