Element A has a half-life of 10 days. A scientist measures out 200 g of this substance. After 30 days has passed, the scientist reexamines the sample.

How much Element A will remain in the sample?

50 g

25 g

12.5 g

100 g

In what form do most ionic compounds occur

An atomic nucleus must contain at least one neutron or else the force of attraction of the electron (s) will collapse the atom. True/false

What does the Aufbau principle state? a. Electrons will be added to an atom in a random order. b. Electrons will be added to an atom starting from the lowest possible level or sublevel. c. Electrons will be added to an atom in a symmetrical manner.

Which object will have the most kinetic energy?

Increasing pressure would most likely increase the reaction rate between which substances? A. A gas and a gas B. A solid and a liquid C. A liquid and a liquid D. A liquid and a gas

How many moles in 68.1 grams of Cu (OH) 2

What happens to the particles in a substance when it is cold?

What is the percent by mass of solute if 14.60g 74.95g of water?

7 An atom that has 13 protons and 15 neutrons is an isotope of the element (1) nickel (3) aluminum (2) silicon (4) phosphorus

The graph below shows how solubility changes with temperature. What is the solubility of Na2HAsO4 at 60°C? 20 g/100 mL of water 46 g/100 mL of water 65 g/100 mL of water 70 g/100 mL of water