What is the number of moles in 500 l of he gas at stp? 0.05 0.2 22 90 what is the percent of the composition of chromium bacro4? 4.87% 9.47% 20.5% 25.2% what is the empirical formula of a substance that is 53.5% c, 15.5% h, 31.1% n by weight c3hn2 c4h14n2 c2h7n ch4n7 the product of a combination reaction is ba(oh)2. if one of the reactants is h2o, what is the other reactant? ba2o bao bah bao2 which of the following is true about single replacement reactions they are restricted to metals they involve a single product two reactants produce two products any metal replaces any other metal. once all answered and finished i will post the whole exam. only if they are answered within 20 minutes. 11: 25am right now.

1 90

29.47%

3 C4H14N2

4 BaO2

Explanation:

1) At STP, 1 mol of gas occupies 22.4 L of volume.

1 L of volume will be occupied by :

Then, 500 L of volume will be occupied by:

There will be 22 moles in 500 L of helium gas at STP.

2) Molecular mass of barium chromate= 253.37 g/mol

Atomic mass of chromium= 52 g/mol

Percentage of an element in a compound:

Percentage of chromium:

20.5% is the percentage of chromium in the given molecular formula.

3)The empirical formula of a substance that is 53.5% C, 15.5% H, 31.1% N by weight.

In 100 g of substance, mass of carbon = 53.5 g

Moles of carbon =

In 100 g of substance, mass of hydrogen= 15.5 g

Moles of carbon =

In 100 g of substance, mass of nitrogen= 31.1 g

Moles of carbon =

For empirical formula, divide smallest number of moles of an element from all the constituting moles of the elements.

Carbon =

Hydrogen =

Nitrogen =

The empirical formula is .

4) Combination reaction is a type of a chemical reaction in which two or more reactant reacts together to give single product.

Oxide of metals are basic  in nature and when they dissolved in water they form basic solution of their respective hydroxide.So, barium hydroxide is made by dissolving barium oxide(BaO) in water.

5)Replacement reaction is defined as chemical reaction in which an element displaces another element from its single compound.

Since, there are two reactants , out of which 1 is reactant compound. Both the reactants reacts to give two products.

i need mutiple choices