Which of the following pairs of elements have the same valence electron configuration?

aluminum (Al) and argon (Ar)
arsenic (As) and gallium (Ga)
fluorine (F) and chlorine (Cl)
lithium (Li) and helium (He)

Nuclear fusion is the source of energy for stars. besides hydrogen, which other element is most likely also common in stars?

When 225mg of anthracene, c14h10(s), was burned in a bomb calorimeter the temperature rose by 1.75k. calculate the calorimeter constant. by how much will the temperature rise when 125mg of phenol, c6h5oh(s), is burned in the calorimeter under the same conditions? (δch< (c14h10,s)=–7061 kj mol−1.)

Write the chemical formula for a compound that is made of an element from group 1 and an element from group 17