1. Choose acids A - H2SO4, B - NaOH, C - HClO4, D - NaHCO3. 2. Classify acids according to their alkalinity: HClO

1. Acid A - H2SO4 is sulfuric acid.
Acid B - NaOH is not an acid, it is actually a base called sodium hydroxide.
Acid C - HClO4 is perchloric acid.
Acid D - NaHCO3 is not an acid, it is actually a salt called sodium bicarbonate.

2. Classification of acids according to their alkalinity:
- HClO is chlorous acid and is weakly acidic.
- H4P2O7 is diphosphoric acid and is moderately acidic.
- H3AsO2 is arsenous acid and is weakly acidic.
- HIO4 is periodic acid and is strongly acidic.
- H2S is hydrosulfuric acid and is weakly acidic.

3. Determining the valence of the acid residue in:
- In HClO4, the acid residue is ClO4. The valence of Cl in ClO4 is +7.
- In H2Se, the acid residue is Se. Selenium typically has a valence of -2.
- In H4XeO6, the acid residue is XeO6. The valence of Xe in XeO6 is +8.

4. Determining the oxidation states of the elements in the acids:
- In H2WO4, the oxidation state of W is +6 and of O is -2.
- In H2MoO4, the oxidation state of Mo is +6 and of O is -2.
- In H3AsO4, the oxidation state of As is +5 and of O is -2.

5. Completing the reaction equations and writing them in full and abbreviated ionic form:
A) BaCl2 + H2SO4 → BaSO4 + 2 HCl
или
Ba^{2+} + 2 Cl^- + 2 H^{+} + SO4^{2-} → BaSO4 + 2 HCl
B) H2CO3 + CaBr2 → Ca(CO3) + 2 HBr
или
H2CO3 + Ca^{2+} + 2 Br^- → Ca(CO3) + 2 HBr
C) H2S + MgCl2 → MgS + 2 HCl
или
H2S + Mg^{2+} + 2 Cl^- → MgS + 2 HCl

6. Establishing a correspondence between the acid formula and its molecular mass:
1) HClO - A - 47
2) HTcO4 - B - 52.5
3) HNO2 - C - 163

7. Selecting substances that...
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