Which of these pairs of elements have the same number of valence electrons?
a) oxygen (o) and bromine (br)
b) selenium (se) and bromine (br)
c) carbon (c) and lead (pb)
d) oxygen (o) and carbon (c)
e) sodium (na) and magnesium (mg)

If 1.63 times 10 negative 4 of helium dissolves in 100.0g of water, what is the concentration in parts per million

Indicate whether the specified alkyl halides will form primarily substitution products, only elimination products, both substitution and elimination products, or no products when they react with sodium methoxide. 1-bromobutane 1-bromo-2-methylpropane 2-bromobutane 2-bromo-2-methylpropane

How many moles of cu are needed to react with 5.8 moles of agno3? cu + 2 agno3 → cu(no3)2 + 2 ag