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
a) The reaction is exothermic since the overall enthalpy change is negative. this means that the system has lost energy to the environment, namely, the apparatus and due to drought.
b) We first calculate the number of moles in 3.55 grams of magnesium.
number of moles= mass/ atomic mass
=3.55/24
=0.1479 moles(to 4sf)
now, if 2 moles of magnesium give -1204kJ
How much energy is given by 0.1479 moles
= (0.1479×-1204kJ)
=-89.0358kJ (don't forget the negative sign)
c) two molesof MgO produces -1204kJ of energy
then -234kJ will be produced by
=(-234kJ×2moles)/1204kJ
=0.3887moles
one mole of MgO weighs 24+16=40
therefore the mass produced is 0.3887moles×40=15.548grams
(d) we first find the number of moles of MgO in 40.3 grams
number of moles=mass/RFM
=40.3g/40= 1.0075moles
if 2 moles of MgO give 1204 kJ then decomposing 1.0075 moles requires
(1.0075 moles×1204kJ)/2=606.515kJ
I assume that it is herring
Answer:
B. first level consumers.
Explanation:
The first level consumers are also the primary consumers. They are the animals that depends or rely on plants to transform chemical energy into carbohydrates and sugar.
Primary consumers are mostly herbivores. They feed on plant matter by which they derive their nutrition. They have special enzymes that helps to convert plant materials into substances needed for their body.
So, the first level consumer takes plant matter and convert them into useful food materials for their own nutrition.
The second level consumers depend on the first level consumers for nutrition.
Answer:
0.39 moles
Explanation:
To find how many moles are in 50.0 g of CaC₂O₄ you divide the grams of the sample by the molar mass of the compound;
=0.39 mol
The grams cancel out and you are left with moles!
I hope this help ^-^
