13) given the redox reaction: cr3+ + al cr + al3+ as the reaction takes place, there is a transfer of a) electrons from al to cr3+ b) electrons from cr3+ to al c) protons from al to cr3+ d) protons from cr3+ to al

Cr³⁺+ Al⁰---> Cr ⁰+ Al³⁺
Cr³⁺+ 3e⁻---> Cr ⁰ 
Cr³⁺ takes electrons to become neutral atom.
 Al⁰---> Al³⁺ + 3e⁻
Al⁰ loses electrons to become ion.

Electrons transferred from  Al to Cr³⁺.
Correct answer is  A) electrons from Al to Cr³⁺.

The answer is a) carbon-12

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 .