What layer of the atmosphere is made mostly of hydrogen and helium?

Which nucleus completes the following equation?

2. A string with a length of 0.9m that is fixed at both ends a) What is the longest possible wavelength for the travelling waves that can interfere to form a standing wave on this string?

Which distance can be most accurately measured with a ruler? a. the size of an object under a microscope b. the width of a book c. the length of a river d. the distance between two cities?

multiply or divide to make this English distance conversion. 174 inches = ___ feet (14.5, 58, 2,088, 23)

beth is traveling east on a dirt road when she spots a pothole ahead. she slows her car from 14.0 m/s to 5.0 m/s in 6.0s. what is the cars acceleration

Water is a compound. O A. True B. False

How do air quality scientists ensure the air is cleaned? What steps do they take?

Is a mirrors surface opaque or transparent or translucent?

Sound waves can combine to become bigger or smaller true or false

Archimedes supposedly was asked to determine whether a crown made for the king consisted of pure gold (density of gold is 19.3 * 103 kg/m3). According to legend, he solved this problem by weighing the crown first in air and then in water.