Half reaction: Cr₂O₇²⁻(aq) + 7H₂O(l) + 6e⁻ → 2Cr³⁺(aq) + 14OH⁻(aq).
Chromium change oxidation number from +6 in dichromate ion Cr₂O₇²⁻ to +3 in chromium cation.
Sum of the charges on the left side of the half reaction is -2 and on the left side is -8 (2·(+3) +14·(-1)), so six electrons must be added on the left side of half reaction.
Hydrogen bonding occurs between a hydrogen atom and an electronegative atom (e.g., oxygen, fluorine, chlorine). The bond is weaker than an ionic bond or a covalent bond, but stronger than van der Waals forces (5 to 30 kJ/mol). A hydrogen bond is classified as a type of weak chemical bond.
An oxide of nitrogen contains 30.45 mass % N, if the molar mass is 90± 5 g/mol the molecular formula is N₂O₄.
<h3>What is molar mass?</h3>
The molar mass of a chemical compound is determined by dividing its mass by the quantity of that compound, expressed as the number of moles in the sample, measured in moles. A substance's molar mass is one of its properties. The compound's molar mass is an average over numerous samples, which frequently have different masses because of isotopes.
<h3>How to find the molecular formula?</h3>
The whole-number multiple is defined as follows.
Whole-number multiple = 
The empirical formula mass is shown below.
Mw of empirical formula = Mw of N+ 2 x (Mw of O)
= 14.01 g/mol + 2 x (16.00 g/mol)
= 46.01 g/mol
With the given molar mass or the molecular formula mass, we can get the whole-number multiple for the compound.
Whole-number multiple =
≈ 2
Multiplying the subscripts of NO2 by 2, the molecular formula is N(1x2)O(2x2)= N2O4.
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Answer: low pressure
Explanation: Air at the equator is warmer and the air above expands, becomes less dense and rises