Answer:
The molality of this solution is 0.368 molal
Explanation:
Step 1: Data given
Mass of CaCl2 = 10.2 grams
Molar mass of CaCl2 = 110.98 g/mol
Mass of water = 250 grams = 0.250 kg
Step 2: Calculate the number of moles CaCl2
Moles CaCl2 = mass CaCl2 / molar mass CaCl2
Moles CaCl2 = 10.2 grams / 110.98 g/mol
Moles CaCl2 = 0.0919 moles
Step 3: Calculate the molality of the solution
Molality solution = moles CaCl2 / mass water
Molality solution = 0.0919 moles / 0.250 kg
Molality solution = 0.368 mol / kg = 0.368 molal
The molality of this solution is 0.368 molal
Answer:
North American X-15
Explanation:
This is the fastest manned aircraft
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.
Answer : 50 electrons are needed to fill all five subshells
Explanation :
To move from Rn to Og, we need to fill 4 subshells which are s, p d & f.
The maximum number of electrons that can be added to each orbital are given below.
s = 2 e⁻
p = 6 e⁻
d = 10 e⁻
f = 14 e⁻
If we add all these electrons, we get 2 + 6 + 10 + 14 = 32 electrons.
We need to add 32 electrons to the atomic number of Rn to get the atomic number of Og.
Hence we say that the atomic numbers of 6th and 7th period elements of the same group differ by 32.
To go from Og to the next noble gas, we have to theoretically fill 5 subshells.
The maximum electrons that can be added to g orbital are 18.
Therefore in order to go from Og to next element, we would add
2 + 6 + 10 + 14 + 18 = 50 electrons.
50 electrons are needed to fill all five subshells.