Circle only those of the following reactions that are redox reactions:
k2cro4 + bacl2 ? bacro4 + 2 kcl
cu+s ? cus
agno3 + hcl ? hno3 + agcl
2 na + 2 h2o ? 2 naoh + h2
mgbr2 + 2 naf ? mgf2 + 2 nabr
2 co + o2 ? 2 co2
so2 + h2o ? h2so3

options B,D and F

Explanation:

Since redox reactions are those which involves both oxidation and reduction

In B , Cu is oxidized and S gets reduced

D, Na gets oxidized and hydrogen gets reduced

F, carbon gets oxidized and Oxygen gets reduced

In g, there is no change in oxidation no of s in both product and Reactants is same +4

Similarly in the case of Ag and Mg.

b) mutualism

hope this : )

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"