Planets in our solar system do not revolve around the sun in perfect circles. Their orbits are more like ovals that scientists describe as which of the following?

A.

revolutionary

B.

rotational

C.

periodical

D.

elliptical

Given the balanced equation: 3fe3 + (aq) + al (s) → 3fe2 + (aq) + al3 + (aq) what is the total number of moles of electrons lost by 2 moles of al (s) ?

The volume of water that must be added in order to dilute 40mL of 9.0M HCl to a concentration of 6.0 M is closest to: (A) 10 mL (B) 20 mL (C) 30 mL (D) 40 mL (E) 60 mL

1. How many grams of nitrogen gas are produced when 47.9 mol of ammonium dichromate are decomposed in the following unbalanced equation? (NH), Cr, O. / (aq) - Cr Og (aq) + H2O + N2 (9)

Identify like terms: 8ab and ab, - 2b and - b

A student states that ALL Substances that are uniform throughout are pure substances. Why is this false?

Which of the following transitions would release energy? n=2->n=3 n=1 - > n=3 n=3 - >n=1 n=3->n=2

Which animal group actually saw a drop in the number of endangered and threatened species between 1995 and 2005? a Fish b. Reptiles c. Birds d. Mammals

Why does burning fossil fuels put ecosystems under pressure?

What is the quantum number set of the ground-state electron that is found in helium (He) but not in hydrogen (H) ? (1, 0, 0, - ½) (1, 0, 1, - ½) (1, 1, 0, - ½) (1, 1, 1, - ½)

What must be true in order for magnetism to induce an electric current in a wire? There needs to be a switch in the circuit. There cannot be a switch in the circuit. The wire must be part of a closed circuit. The wire must be part of an open circuit.