Which of the following is a physical change

A copper roof changing colors from orange to green

Sawing a piece of wood in half

Rust forming on an iron fence

Burning a piece of wood

What is the mass of a sample of NH3 containing 7.20 * 1024 molecules of NH3? 161 grams 187 grams 203 grams 214 grams

Consider the following reversible, exothermic chemical reaction: 2C2H2 (g) + 5O2 (g) ↔4CO2 (g) + 2H2O (g) All BUT one of the conditions will cause equilibrium to shift right and produce more of the products.

Why had americans developed a tradition of waste?

1. What is the probability of rolling a five on one die three times in a row? 2. The allele for a cleft chin, C, is dominate among humans. Using a punnet square, what are the results of a cross between parents with genotypes Cc and cc

Mercury (II) oxide (HgO) decomposes to form mercury (Hg) and oxygen (O2). The balanced chemical equation is shown below. 2HgO 2Hg + O2 The molar mass of HgO is 216.59 g/mol. The molar mass of O2 is 32.00 g/mol.

Under which conditions would the solubility of a gas be greatest? A. high pressure and high temperature B. high pressure and low temperature C. low pressure and high temperature D. low pressure and low temperature

How many milliliters is 0.55 L? O A. 1000 ml OB. 0.00055 mL O C. 550 ml D. 55 mL

When a warm front passes your location, the temperature rises rapidly. As a result, air density: B? increases decreases remains the same

A scientist wished to carry out a chemical reaction in which two moles of aluminum combine with three moles of sulfur. He has 2.70 g of aluminum to react. How many grams of sulfur must he take to satisfy all the aluminum atoms? 1.51 g 2.14 g 3.

Determine the equilibrium pH and speciation (concentration of each species) of the following two solutions. Neglect activity corrections. Species added Total concentration (solution a) HCl 10-3 M (solution b) NaCl 10-3 g.