When the following equation is balanced, the coefficient in front of PbBr2 is ZnBr2 + Pb(NO2)2 → Zn(NO2)2 + PbBr2

A.2
B.3
C.1
D.4

1

Explanation:

Refer to the attachment for proof

30litre of li2o is 1.0002mole approximately 1 mole

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .