This question is about reactions of metals. Figure 1shows what happens when calcium, copper, magnesium and zinc are added to hydrochloric acid. Figure 101.1What is the order of decreasing reactivity of these four metals?[1 mark]Tick()onebox. Zn Ca Cu MgCa Cu Mg ZnCu Zn Ca MgCa Mg Zn Cu

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 .

(no3)⁻n has oxidation number x,o has oxidation number -2.(x*1 -2*3) charge of the nitrate ion, and we know that charge of the nitrate ion =-1.so,(x*1 -2*3) =-1x-6=-1x=+5answer a. +5.