Answer:
The reflection of sound waves
Explanation:
An echo is a reflection of sound that bounces of of one thing to another.
Answer:
2.89 g/cm^3
Explanation:
Since density equals mass over volume (or also seen as 
), simply divide 66.5 grams by 23.0 cm. This will output an answer of 2.89 g/cm^3.
2NaCN(s) + H₂SO₄(aq) --> Na₂SO₄(aq) + 2HCN(g)
The molar ratio between NaCN : HCN is 2:2 or 1:1
Mass of HCN = 16.7 g
Molar mass of HCN = 1 + 12 + 14 = 27 g/mol
Molar mass of NaCN = 49 g/mol
Therefore, the mass of NaCN is
16.7 g of HCN x 49 g/mol of NaCN / 27 g/mol of HCN = 30.3 grams of NaCN
Therefore, 30.3 grams of NaCN gives the lethal dose in the room.
Cobalt sulphate is the usual source of water-soluble cobalt since it is the most economical salt and shows less tendency to deliquesce or dehydrate
AgNO₃+NaCl⇒AgCl+NaNO₃
<h3>Further explanation</h3>
Double-Replacement reactions. Happens if there is an ion exchange between two ion compounds in the reactant to form two new ion compounds in the product
Reaction
AB + CD⇒AD + CB
So for the option :
1. synthesis/combination reaction
2. decomposition reaction
3. double replacement reaction
4. single replacement reaction
