1. 9. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 3d 5 How many neutrons in the element depict
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Question
1. 9. 1s2 2s2 2p6 3s2 3p6 4s1 3d5
How many neutrons in the element depicted above?
Answer:
2. 110. Choose the correct value for the total number of molecules in 5 g of sodium carbonate.
Choose one answer.
A. 7.26 x 10^22
B. 3.63 x 10^22
C. 6.02 x 10^23
D. 82.99
3. 11. 1s2 2s2 2p6 3s2 3p6 4s1 3d5
How many valence shell electrons are in this element?
Choose one answer.
A. 1
B. 11
C. 5
D. 6
de112.Identify the following compounds as either ionic, covalent or polar.
Potassium nitrate
Choose...ionicpolarcovalent
Methane CH4
Choose...ionicpolarcovalent
Barium chloride
Choose...ionicpolarcovalent
Perchloric acid
Choose...ionicpolarcovalent
Water
Choose...ionicpolarcovalent
Hydroxyl (-OH)
Choose...ionicpolarcovalent
Iron (II) oxide
Choose...ionicpolarcovalent
5. 13. In order for elements to covalently bind, atoms must have _____ electrons available to form the compound.
Choose...octet ruleisotopesvalencepolar
Nobel gases follow the _____ ______ that every molecule or compound seeks to achieve in a chemical reaction.
Choose...octet ruleisotopesvalencepolar
Ice floats on water because of water's _____ nature.
Choose...octet ruleisotopesvalencepolar
Naturally occuring and man made _____ contribute to the variety of elements and the average masses.
Choose...octet ruleisotopesvalencepolar
6. 14. Magnesium is present in magnesium sulfate at what percent?
Choose one answer.
A. 26.6
B. 53.1%
C. 20.2%
D. 12.038%
7. 15. Antimony (Sb) consists of two isotopes, 123Sb and 121Sb. The atomic mass percent of 121Sb is 1.1%. What is the atomic mass of 123Sb if the overall atomic mass is 121.76 ?
Choose one answer.
A. 100
B. 13.4
C. 120.4
D. 97.9
E. 121.75
8. 16. 1s2 2s2 2p6 3s2 3p6 4s1 3d5
The configuration above is that of the element________ .
Answer:
A. 7.26 x 10^22
B. 3.63 x 10^22
C. 6.02 x 10^23
D. 82.99
Explanation / Answer
1.it is configuration of Chromium.
mass no of Cr = 52,
so no of neutrons = 52-24 = 28
2. moles = 5/(MW of Na2Co3)=5/106,
so no of molecules = 5/106 * 6.02 x 10^23 =2.84*10^22
3.valence shell is 4th ..which contains only 1 electron
4.KNO3- ionic
CH4- covalent
BaCl2- ionic
Perchloric acid -polar covalent
water-polar
O-H -polar
ioron oxide - ionic
5.1)valence
2) octet rule
3)polar
4)isotopes
6) MgSO4....Molecular weight = 120
atomic mass of Mg = 24.3,
so % of mg present = 24.3/120 =20.2 %
7)using average rule,
if x be the required atomic mass,
x* (1-0.011) + 121* 0.011 = 121.76
solving it,
x =121.75 g(actually i 'm getting 121.768) but there is no option..but the closest option is 121.75)
8. chromium
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