Which is an example of a chemical reaction? A) melting ice B) rusting iron C) water evaporating D) rubbing a marker on paper

Element X has two naturally-occurring isotopes. X-10 has a 19.9% abundance and X-11 has an 80.1% abundance. What is most likely the identity of element X?

Which of the following statements is true? 1. Dalton believed atoms were made mostly of empty space. 2. Plasmas have a net negative charge. 3. The number of protons in an element is always equal to the number of neutrons. 4.

When the reaction p4o10 + koh → k3po4 + h2o is balanced, how much koh is required to react with 3 moles of p4o10? 1. 9 mol 2. 3 mol 3. 18 mol 4. 36 mol 5. 27 mol?

What experiment led to the discovery of the nucleus

if 1200 j of heat were absorbed by a 25 g block of iron, by how much would the temperature of the iron increase?

How do you know if the reaction is exothermic or endothermic if both phase are same?

How many elements are in a set whole numbers between 3 and 15

Calculate the percent activity of the radioactive isotope strontium-89 remaining after 5 half-lives.

Describe 2 theories for yawning

When a bimetallic bar made of copper and iron strips is heated, the bar bends toward the iron strip. the reason for this is?