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chemically balance the following:

Mg(OH)2 + __ HCl → MgCl2 + __ H2O

CH4 + O2 → CO2 + H2O

___ Cu + ___ Br2 → ___ CuBr2

Balance and in which category does it fit in? single or double displacement or synthesis or decomposition? (a) k2 o → k + o2 (b) na + i2 → nai (c) cu(no3 )2 + naoh → cu(oh)2 + nano3 (d) kclo3 → kcl + o2 (e) ca(no3 )2 + hbr → cabr2 + hno3 (f) sn(oh)2 → sno + h2 o (g) p4 + n2 o → p4 o6 + n2 (h) fe + al2 (so4 )3 → feso4 + al (i) alcl3 + na2 co3 → al2 (co3 )3 + nacl (j) c3 h6 + o2 → co2 + h2 o

How does science use models to gain a better understanding of concepts?

372 ml is the volume of aluminum, density is 2.70 g/ml what is the mass in grams