Q: The burning of what type of fuels is a major source of sulfur oxides and nitrogen oxides? Choices: - biofuels - renewable - synthetic - fossil A:
fossil

(Question)
Q: Why do comet tails always point away from the sun instead of trailing behind the comet? Choices: - dust particles attract - dust particles evaporate - dust particles liquify - dust particles recoil A:
(Answer)
dust particles recoil

Ques: Q: Isotopes have the same number of protons and electrons, but a different number of what? Choices: - reactions - impurities - atoms - neutrons A:
Ans: neutrons

(Q).
Q: Which theory describes the benzene molecule and other planar aromatic hydrocarbon molecules as hexagonal rings of sp2-hybridized carbon atoms with the unhybridized p orbital of each carbon atom perpendicular to the plane of the ring? Choices: - hybrid orbital theory - covalent bond theory - molecular orbital theory - valence bond theory A:
(A).
valence bond theory

Ques:Q: What part of the cell does cellular respiration occur? Choices: - glucose - proton - nuclei - mitochondria A:

Ans:mitochondria

Ques: Q: A lake is an example of what type of biome? Choices: - natural biome - wet biome - organic biome - freshwater biome A:
Ans:
freshwater biome