9.

The atomic number of an element is the total number of which particles in the nucleus?

a. electrons

protons and electrons

neutrons

d. protons

The nucleus of an isotope of chlorine contains 20 neutrons

Dinitrogen difluoride gas is collected at 5.0 °C in an evacuated flask with a measured volume of 50.0 L. When all the gas has ben collected, the pressure in the flask is measured to be 0.

Which of the following compounds contains the Mn3 + ion A. MnBr2 B. MnS C. MnO D. Mn2O3

Identify the double displacement reactions among the following: 1. KCl (aq) + AgNO3 (aq) - AgCl (s) + KNO3 (aq) 2. Na2SO4 (aq) + BaCl2 (aq) →BaSO4 (s) + 2NaCl (aq) 3.

The atomic mass of 13C is 13.003355. Multiply the atomic mass of 13C by its abundance. Report the number to 8 significant digits.

Which statements indicate what the fossil record suggests about evolution on Earth? Check all that apply. Humans have only recently existed on Earth. Organisms originally lived only in Earth's water. Life on Earth started when water formed on Earth.

What does homogeneous mixture of elements mean

As an acid is added to neutral water the [OH-] will

What is the mass in grams of 5.00moles of CH4? How many moles of oxygen gas O2, are present in a 38g sample of O2

25 In general, for a gas at a constant pressure, A the temperature of the gas is inversely proportional to its volume B. the temperature of the gas is inversely proportional to its pressure C.