Answer:
- Question 19: the three are molecular compounds.
Explanation:
<em>Question 19.</em>
All of them are the combination of two kinds of different atoms in fixed proportions.
- C₂H₄: two carbon atoms per four hydrogen atoms
- HF: one hydrogen atom per one fluorine atom
- H₂O₂: two hydrogen atoms per two oxygent atoms
Thus, they all meet the definition of compund: a pure substance formed by two or more different elements with a definite composition.
Molecular compounds are formed by covalent bonds and ionic compounds are formed by ionic bonds.
Two non-metal elements, like H-F, C - C, C - H, H-O, H - H, and O - O will share electrons forming covalent bonds to complete their valence shell. Thus, the three compounds are molecular and not ionic.
<em>Question 20. </em>Formula of copper(II) sulfate hydrate with 36.0% water.
Copper(II) sulfate is CuSO₄. Its molar mass is 159.609g/mol
Water is H₂O. Its molar mass is 18.015g/mol
Calling x the number of water molecules in the hydrate, the percentage of water is:
From which we can solve for x:
Thus, there are 5 molecules of water per each unit of CuSO₄, and the formula is:
Answer:
-Unknown
Explanation:
Questions is not seen properly bro
I believe the answer is D.
Scientists are biased, and want to prove their specific hypothesis is right.
<u>Answer:</u> The temperature increase will be 31.70°C.
<u>Explanation:</u>
To calculate the increase in the temperature of the system, we use the equation:
where,
q = Heat absorbed = 36.5 kJ = 36500J
m = Mass of water = 275 g
c = Specific heat capacity of water = 
= change in temperature = ? °C
Putting values in above equation, we get:
Hence, the temperature increase will be 31.70°C.
Answer:- D. Double- replacement reaction
Explanations:- In general, the decomposition reactions looks like:
The given reaction looks different than this and so it is not decomposition reaction.
A single-replacement reaction looks like:
Our reaction looks different from this so single-replacement is also not correct.
Synthesis reaction looks exactly opposite to decomposition reaction.
The given reaction is different than this and so it is not synthesis reaction also.
A double-replacement reaction looks like:
In this reaction, the ions are exchanged as could be seen in the general reaction. On reaction side,A is with B and C is with D. On product side, A is with D and C is with B.
The same is happening in the given reaction. Nitrate ion is with lead metal on reactant side and chlorine is with hydrogen, On product side, Chlorine is with lead metal and nitrate ion is with hydrogen. So, ion exchange has taken place here and so this is a double-replacement reaction and choice D is correct.
