Explain how scientists know that the universe is expanding and who was the first to say this

Which characteristic is given by principal quantum number?

She slams her fist onto the calculator with 8000 j of KE. If she moved her arm at 3 m/s, what is the mass of her fist?

1. Johan started attending swimming lessons. On the first day, he suffered from pain on his body as he had used a wrong technique to jump into the water. Explain the reason for Johan's injury. (Relate to water surface tension).

Usable chemical energy in food begins as energy

An unknown compound has a percent composition of 52.10% potassium, 15.8% carbon, and 32.1% oxygen. The molar mass of the compound is 150.22 g/mol. What is the empirical formula and the molecular formula of this compound? A. KCO and K2C2O3 B.

Which of the following should be done when designing an experiment for a controlled scientific investigation? A. list the procedures B. plan the variables C. list the needed materials D. all of these

Assuming the octet rule is obeyed, how many bonds and how many lone pairs will atoms of oxygen (o) and nitrogen (n) have in order to have formal charges of + 1?

Explain why animals must eat food, but plants do not have to.

What is the theoretical yield of moles of hydrogen that can be produced from 0.032g of MG?

What did JJ Thomson think the Atom looked like?