Is CO2 is a molecule or a element or a compound

Find the momentum for a 2.6-kg brick parachuting straight downward at a constant speed of 8.4 m/s .

Which of the following is another term for a planned economy

Atoms seldom exist as independent particles in nature a) as single particles, most atoms have low potential energy b) their electronegativity is much lower when they combine with other atoms c) atoms are more stable when they combine with other atoms d) neutral particles are rare