Answer:
Explanation:
You just have to see the REACTANTS and PRODUCTS and look how much molecules are there and accordingly put numbers.
Eg:4Fe+3O2--------->2Fe2O3
Reaction 3 is the double displacement reaction.
Double displacement reaction occurs when the negatively and the positively charged ions of the compounds interchange their position when the new compound in the product is formed.
<h3>Which is a double displacement reaction?</h3>
In the <u>first reaction</u>, the element lead (Pb) is not an ion and no exchange of the cations or the anions occurs hence it is not a double displacement reaction.
In the <u>second reaction</u>, one compound is getting split into two new compounds and is a decomposition reaction.
In the <u>third reaction</u>,
in
and
in
are anions and cations and exchanges their places to produce two new compounds 
In the <u>fourth reaction</u>, a single compound is generated as the result of the combination reaction and hence, it is not the double displacement reaction.
Therefore,
is the double displacement reaction.
Learn more about double displacement reaction here:
brainly.com/question/10091171
Answer:C
Explanation: The mass is still the same even though they took it apart.
Complete Question:
This diagram shows a marble with a mass of 3.8 grams (g) that was placed into 10 milliliters (mL) of water. Using the formula V M D = , what is the density of the marble?
(See attachment for full diagram)
Answer:
1.27 g/cm³
Explanation:
First, find the volume of rock:
Volume of rock = volume of water after rock was placed - volume of water before rock was placed
Volume of rock = 13 - 10 = 3ml
Density of rock = grams of rock per 1 cm³
Note: 1 ml = 1 cm³
Let x represent amount of rock per 1 cm³
Thus,
3.8g = 3 cm³
x = 1 cm³
Cross multiply
1*3.8 = 3*x
3.8 = 3x
3.8/3 = 3x/3
1.27 = x
Density of rock = 1.27 g/cm³
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