A cast fossil is formed when

A) an organism leaves an impression in rock

B) an organism leaves a footprint

C) minerals fill in an impression left by an organism

D) when the remains of a living thing are preserved and turned into rock

Determine the number of moles of H in each sample. 1). 8.48 mole NH3 2).0.111 mole N2H4 3). 36.0 mole C10 H22

How many molecules of F2 react with 66.6 g NH3? (stoichiometry)

A student heats a sample of KClO3, KCl, and MnO2 having a mass of 3.63.49 g. After the reaction is complete, she has collected 346.2 mL of oxygen in a water filled flask. The room temperature is 23.6 degrees C and the atmospheric pressure is 763.

A scientist notices that a lump of niobium is warm to the touch and wonders if nuclear reactions are taking place in the metal. How can she find out? A. Measure the metal's temperature. B. Check for the presence of alpha, beta, and gamma particles.

During which process does the nucleus of an atom undergo change?

Hydrochloric acid is purchased in 12 molar concentrations. If I needed 200 ml of 2.0 molar HCl, how many milliliters of the concentrated solution would I need

Which of the following represents a chemical change? Bending a wire Freezing of water Fireworks exploding Melting of a wax candle

5.00 L of a gas is collected at 100K and then allowed to expand to 20.0 L. What must the new temperature be in order to maintain the same pressure? A. 400 °C B. 127 °C C. 223 °C D. 627°C

Before the initial explosion was the matter hot or cold

Which of the following atoms has seven valence electrons? chlorine (Cl) nitrogen (N) manganese (Mn) oxygen (O)