Silicon has three naturally occurring isotopes with thefollowing masses and natural abundances: Isotope Mass ({\rm amu}) Abundance (%)
{\rm Si}-28 27.9769 92.2
{\rm Si}-29 28.9765 4.67
{\rm Si}-30 29.9737 3.10
Calculate the atomic mass of silicon.
b- When solutions of silver nitrate and calcium chloride aremixed, silver chloride precipitates out of solution according tothe equation
2\; \rm AgNO_3 \it (aq) \rm \;+\;CaCl_2 \it (aq) \rm \; \rightarrow \; 2\;AgCl \it (s) \rm\; + \; Ca(NO_3)_2 \it (aq)
What mass of silver chloride can be producedfrom 1.18 L of a 0.113 \it M solution of silver nitrate?
The reaction described required3.28 L of calcium chloride. What is the concentration of thiscalcium chloride solution?
c- A volume of 50.0 mL of aqueous potassium hydroxide (\rm KOH) was titrated against a standard solution of sulfuricacid (\rm H_2SO_4). What was the molarity of the \rm KOH solution if 23.7 mL of 1.50 M\rm H_2SO_4 was needed? The equation is
\rm 2KOH(\it aq\rm )+H_2SO_4(\it aq\rm )\rightarrow\rm K_2SO_4(\it aq\rm )+2H_2O(\it l\rm )
Then, Redox titrations are used to determine the amounts ofoxidizing and reducing agents in solution. For example, a solutionof hydrogen peroxide, \rm H_2O_2, can be titrated against a solution of potassiumpermanganate, \rm KMnO_4. The following equation represents the reaction:
\matrix{{\rm 2KMnO}_4(aq)+{\rm H_2O}_2(aq)+3{\rm H_2SO}_4(aq)\rightarrow&&\h fill\cr\hfill \qquad\qquad\qquad{\rm O}_2(g)+2{\rm MnSO}_4(aq)+{\rm K_2SO}_4 (aq)+4{\rm H_2O}(l)&&\hfill}
A certain amount of hydrogen peroxide was dissolved in 100.\rm mL of water and then titrated with 1.68 M\rm KMnO_4. How much \rm H_2O_2 was dissolved if the titration required13.8 mL of the \rm KMnO_4 solution?

See explanation

Explanation:

Relative atomic mass of silicon;

(27.9769  ×  0.9218)  +  (28.9765  ×  0.0471)  +  (29.9738  ×  0.0312) = 28.0891

2)

2AgNO3 (aq) + CaCl2(aq) ----> 2AgCl(s) + Ca(NO3)2(aq)

number of moles of silver nitrate = 1.18 L * 0.113 M = 0.133 moles

Since 2 moles of silver nitrate yields 2 moles of silver chloride

0.133 moles of silver nitrate yields 0.133 * 2/2 = 0.133 moles of AgCl

Since 2 moles of silver nitrate reacts with 1 mole of calcium chloride

0.133 moles of silver nitrate reacts with  0.133 moles * 1/2 = 0.0665 moles of CaCl2

n =CV

C =n/V = 0.0665 moles/3.28 L = 0.02 M

3) H2SO4(aq) + 2KOH(aq) -------> K2SO4(aq) + 2H20(l)

CA = concentration of acid = 1.5 M

VA = volume of acid  23.7 ml

CB = concentration of base = ?

VB= volume of base = 50 ml

NA = number of moles of acid =1

Number of moles of base = 2

From;

CAVA/CBVB =NA/NB

CAVANB = CBVBNA

CB = CAVANB/VBNA

CB = 1.5 * 23.7 * 2/ 50 * 2

CB = 0.711 M

4) Number of moles of KMnO4 = 1.68 * 19.8/1000 = 0.033 moles

If 2 moles of KMnO4 reacts with 1 mole of H2O2

0.033 moles of KMnO4 reacts with  0.033 * 1/2 = 0.0165 moles of H2O2

molar mass of H2O2 = 34 g/mol

mass of H2O2 = 0.0165 moles of H2O2 * 34 g/mol = 0.56 g of H2O2

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.

more infor would

a lot