Answer:
pH= 12
Explanation:
Potassium hydroxide (KOH) is a strong base, so it dissociates completely in water by giving OH⁻ anions as follows:
KOH⇒ K⁺ + OH⁻
Since dissociation is complete, it is assumed that the concentration of OH⁻ is equal to the initial concentration of KOH:
[OH⁻]= [KOH]
In order to find the initial concentration of KOH, we have to divide the mass (0.140 g) into the molecular weight of KOH (Mw):
Mw (KOH)= K + O + H = 39 g/mol + 16 g/mol + 1 g/mol = 56 g/mol
moles KOH: mass/Mw= 0.140 g/(56 g/mol) = 2.5 x 10⁻³ moles
The molality of the solution is the number of moles of KOH per liter of solution:
V= 250.0 ml x 1 L/1000 ml= 0.250 L
M = (2.5 x 10⁻³moles)/(0.250 L)= 0.01 M
Now, we calculate pOH:
pOH = -log [OH⁻]= - log [KOH]= -log (0.01) = 2
Finally, we calculate pH from pOH:
pH + pOH = 14
⇒pH = 14 - pOH= 14 -2 = 12
Answer:
Q1. D) A single replacement reaction takes place because sodium is more reactive than hydrogen.
Explanation: 
Sodium metal reacts with water to givesodium hydroxide and hydrogen gas. A single replacement reaction takes place because sodium is more reactive than hydrogen.
Sodium easily lose electrons than hydrogen and get oxidized to 
and 
get reduced to give 
.
Q2. B) It is a single replacement reaction, and the cations in the two ionic compounds are different.
Explanation: 
where Sodium is a metal and 
is an ionic compound. Na being more reactive than Al, displaces it from its salt solution.
Q3. D) 
Explanation: A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution.Thus zinc can easily lose electrons as compared to hydrogen and result in the formation of zinc sulfate and hydrogen.
Q4. False
no reaction
Explanation: As zinc lies lower in reactivity series, it is less reactive than calcium. It will not be able to displace calcium from its salt and hence no reaction occur. Thus the given statement is false.
Q5. False
Explanation: A double displacement reaction is one in which exchange of ions take place. Thus an element replaces another element and not same element.
A single replacement reaction is one in which a more reactive element displaces a less reactive element from its salt solution. Thus one element should be different from another element.
Q6. A)
, because K retains the same charge throughout the reaction
Explanation: A balanced chemical reaction is one in which the number of atoms on both sides of a chemical equation are same. Also K has an oxidation state or charge of +1 in 
as well as 
Mass = 14.0 g of mercury is formed, 22.6 grams of mercury nitrate, hg(no3)2 reacts with an excess of potassium, k.
An inorganic substance with the formula Hg(NO3)2xH2O is mercury nitrate. Hot, concentrated nitric acid is used to process mercury to create it. By using X-ray crystallography, neither anhydrous nor monohydrate have been verified. The drug might have an impact on the kidneys, peripheral nervous system, and central nervous system. Ataxia, tremors. Given data: Mass of mercury nitrate = 22.17 g, Mass of mercury formed = ?
Solution:
Chemical equation:
Hg(NO₃)₂ + 2K → 2KNO₃ + Hg
Number of moles of mercury nitrate:, Number of moles = mass/molar mass, Number of moles = 22.17 g / 324.6 g/mol, Number of moles = 0.07 mol, Now we will compare the moles of Hg(NO₃)₂ and mercury.
Hg(NO₃)₂ : Hg
1 : 1
0.07 : 0.07
Mass of mercury: Mass = number of moles × molar mass, Mass = 0.07 mol × 200.6 g/mol
Mass = 14.0 g
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Answer:
atomic weight..................
