Question

96.   Name three indicators of chemical change.
97.   Make the following conversions:
   a.   66.5 mm to micrometers
   b.   4 × 10−2 g to centigrams
   c.   5.62 mg/mL to decigrams per liter
   d.   85 km/h to meters per second
98.   How many significant figures are in each measurement?
   a.   0.00052 m
   b.   9.8 × 104 g
   c.   5.050 mg
   d.   8.700 mL
99.   How many neutrons are in each atom?
   a.   silicon-30
   b.   magnesium-24
   c.   nitrogen-15
   d.   chromium-50
100.   How do isotopes of an atom differ?
101.   In a neutral atom, the number of which two subatomic particles must always be equal?
102.   How many electrons are in the 2p sublevel of an atom of each element?
   a.   aluminum
   b.   carbon
   c.   fluorine
   d.   lithium
103.   What happens to the wavelength of light as the frequency increases?
104.   What does the 5 in 3d5 represent?
105.   Write correct electron configurations for atoms of the following elements:
   a.   sodium
   b.   sulfur
   c.   phosphorus
   d.   nitrogen

Answer 1

“96. Name three indicators of chemical change.

The indicators of chemical change are

1) Change in temperature
2) Formation of precipitate (solid)
3) Formation of gas (bubbles)
4) Change in colour
5) Formation of odour

97.   Make the following conversions:
   a.   66.5 mm to micrometers ======> 66500 micrometers
   b.   4 × 10−2 g to centigrams======> 4 cg
   c.   5.62 mg/mL to decigrams per liter======> 562 dg/L
   d.   85 km/h to meters per second======> 85 x 10^3 m/ 60x 60 s======> 23.61 m/s

98. How many significant figures are in each measurement?
   a.   0.00052 m======> 2 significant figure
   b.   9.8 × 104 g======> 2 significant figure
   c.   5.050 mg======> 4 significant figure
   d.   8.700 mL======> 4 significant figure

99.    How many neutrons are in each atom?
   a.   silicon-30   ======> 16 electrons
   b.   magnesium-24 ======> 12 electrons
   c.   nitrogen-15 ======> 8 electrons
   d.   chromium-50 ======> 26 electrons

100.   How do isotopes of an atom differ?

The isotopes of an element have same atomic number(number of electrons/protons) but different atomic masses(number of electrons + neutrons).so,they are different from each other on the basis of number of neutrons.

101.   In a neutral atom, the number of which two subatomic particles must always be equal?  

Electrons and protons, are the two subatomic particles must always be equal in neutral atom.

102.   How many electrons are in the 2p sublevel of an atom of each element?
   a.   aluminum =====> 6 electron in 2p sublevel of an atom
   b.   carbon =====>2 electron in 2p sublevel of an atom
   c.   fluorine=====> 5 electron in 2p sublevel of an atom
   d.   lithium=====> 6 electron in 2p sublevel of an atom

103. What happens to the wavelength of light as the frequency increases?

             As the frequency increases then wavelength decreases (inversely proportional).

104. What does the 5 in 3d5 represent?

            5 stands for the number of electrons present in the 3d orbital.

105. Write correct electron configurations for atoms of the following elements:
   a.   sodium =======> 1s2, 2s2, 2p6, 3s1
   b.   sulfur======> 1s2, 2s2, 2p6, 3s2 3p4
   c.   phosphorus====>1s2, 2s2, 2p6, 3s2 3p3
   d.   nitrogen”======> 1s2, 2s2, 2p3