General Chemistry Chapters 19, 21, 22

Topics: Ligand, Radioactive decay, Neutron Pages: 15 (1188 words) Published: October 17, 2013
HOMEWORK EXAM 3:

Chapter 19:

The half life of 90Sr is 29 years.  What fraction of the atoms in a sample of 90Sr would remain 175 years later? Answer

0.166      

0.125     

0.062      

here
0.015 

Which relation is not correct?
Answer

11p = 11H = proton

0-1e = 0-1β = electron

here
+10e = +10β= positron

10n = neutron

As a result of beta decay, the product nucleus is
Answer

one atomic number lower than the original element.

two atomic number higher than the original element.

here
one atomic number higher than the original element.

two atomic number lower than the original element.
What is X for the nuclear reaction: 21284Po  à  20882Pb  +  X Answer

42p

1-1β

here
42α

11n

Which statement is not correct for the nuclear reaction:  146C  à  147N  +  0-1β ? Answer

C is radioactive.  

Nucleus of C is not stable.   

Here?
N lies above the belt of stability of nucleus.

One neutron in the nucleus of C converts to a proton with the release of the release of particle.

If 12% of a certain radioactive isotope decays in 5.2 years, what is the half-life of this isotope?  Answer

0.59 yr

1.7 yr

21.7 yr

here
28.1 yr

Which statement is false?
Answer

No chemical treatments can make radioactive elements harmless.   

The rate of decay (disintegration) of U-238 is proportional to its sample size.   

Changes in temperature or pressure cannot affect the rate of decay (disintegration) of radioactive elements.    

F
Decay constant maintains its constancy only at the specific temperature. 

How much energy is lost or gained when a mole of cobalt-60 undergoes beta decay: 6027Co    -->   6028Ni    +    0-1e ?
The mass of the 6027Co atom is 59.933819 amu, and that of a 6028Ni atom is 59.930788 amu. Answer

Here?
2.724x1011 J energy is released.

2.724x1011 J energy is absorbed.

2.724x108 J energy is released.

2.724x108 J energy is absorbed.

Write a balanced nuclear equation for the reaction in which oxygen-15 undergoes positron emission. Answer

158O  -->  159F  +  0-1n

158O  -->  148O  +  10e

158O  -->  159F  +  0-1e

here
158O  -->  157N  +  01e

What element undergoes alpha decay to form lead-208?
Answer

here
21284Po

20484Po

21282Po

20482Po

CHAPTER 21
Which process is not a part of the purification metals?  
Answer

distillation

electrolysis

zone refining

here
chemical reduction

By what kind of element can a n-type semiconductor be doped? Answer

B

Al

Here, As, Antimony
P

S

By what kind of element can a p-type semiconductor be doped? Answer

Mg

Here and Al
B

P

S

Which process does not show the production of metal by chemical reduction? Answer

V2O5(s)   +   5Ca(l)    -->    2V(l)   +   5CaO(s)

TiCl4(g)    +    2Mg(l)    -->    Ti(s)    +    2MgCl2(l)

roasting
CaCO3(s)     -->     CaO(s)      +      CO2(g)

Cr2O3(s)    +    2Al(s)    -->    2Cr(l)    +    Al2O3(s)

Which one of the following is the best semiconductor?
Answer

Cu

here
Si

Zn

Co

What is amalgam?
Answer

an alloy of aluminum with another metal or metals.

here
an alloy of mercury with another metal or metals.

an aluminium bauxite mixture

an aluminum ferromagentic metals

What is a p-type semiconductor?
Answer

A semiconductor that contains donor impurities which have excess electrons.

A semiconductor that contains acceptor impurities which have excess electrons.

A semiconductor that contains donor impurities which are electron deficient. T

A semiconductor that contains acceptor impurities which are electron deficient.

What is doping?
Answer

Enhancing the ability of a semiconductor to conduct heat by adding small amount of certain impurities to the element.

Enhancing the ability of...
Continue Reading

Please join StudyMode to read the full document

You May Also Find These Documents Helpful

  • APUSH CHAPTER 21 AND 22 Essay
  • Chemical Reaction and General College Chemistry Essay
  • Essay about General Chemistry
  • Chapter 22 Research Paper
  • General Chemistry Essay
  • Chemistry Essay
  • Chapter 21 Essay
  • chemistry Essay

Become a StudyMode Member

Sign Up - It's Free
Call Recorder - Automatic 1.1.114 APK | Watch Movie | Coles Little Shop Mini Collectibles Cheap Limited Time Only Kids New 1 minis