Which option describes a similarity and a difference between isotopes of an element?

Lanthanum-138 has a half-life of 105 billion years. After 525 billion years, how much of a 240 g sample of this radioisotope will remain? nevermind, I got 7.5g and was right

Why does one mole of H2O correspond to

Which of the following is considered a hypothesis as opposed to an observation

What is the ph of a solution of 0.20 m hno2 containing 0.10 m nano2 at 25°c, given k a of hno2 is 4.5 * 10-4?

A 0.500-g sample of tin foil reacted with oxygen to give 0.635 g of product. calculate the empirical formula of the tin oxide.

Hydrogen is an element with two naturally occurring isotopes: 2 H and 3 H. This means that 2 H, which has a mass number of 2, has fewer than 3 H, which has a mass number of 3. True/False

C₂H₂ + O2 - CO₂ + H₂ How many moles of oxygen are necessary to react completely with 4.0 moles of propane (CH) ?

What are the two main classifications of energy resources?

A liquid is heated and a solid forms at the bottom of the beaker. Is this a physical or chemical change?

How to predict the formula of an ionic compound based on the charges of the ions?