Chemistry - December 2007

1: The equation 92U238 + 0n1 --> 92U239 represents
an electronic reaction
a molecular reaction
a nuclear reaction
an oxidation reaction


2: In the hydrogen bomb the fusion of hydrogen isotopes results in the production of
barium
helium
plutonium
proton


3: The atom whose nucleus contains the largest number of neutrons is
92U235
92U239
93Np239
94Pu239


4: Neutrons are best absorbed in an atomic pile by rods of
cadmium
calcium
copper
zinc


5: A man-made element is
gold
plutonium
sodium
zinc


6: Radioactive changes differ from ordinary chemical changes because radioactive changes
are explosive
absorb energy
involve changes in the nucleus
release energy


7: Two man-made elements with atomic numbers greater than 92 are
americium and curium
thorium and actinium
U238 and U239
U235 and U238


8: Isotopes of uranium have different
atomic numbers
atomic weights
numbers of planetary electrons
numbers of protons


9: The Law of Conservation of Mass-Energy states that matter may be converted into __________.
atomic charge
energy
mass
liquid


10: In reactions involving atomic energy changes take place in the _______ of an atom.
proton
valence shell
neutron
nucleus


11: A substance which slows down neutrons so that they may be captured in an atomic pile is known as the __________.
moderator
graphite
slowing rod
inhibitor


12: The rate at which an atomic pile operates is controlled by rods of ______________ or boron steel.
aluminum
boron aluminum
zinc
cadmium


13: As radium is disintegrated, its half-life ____________.
increases
decreases
remains the same
none of the above


14: When a radioactive element undergoes beta disintegration, the atomic number of the nucleus
increases
decreases
remains the same
none of the above


15: As the number of neutrons emitted during a fission reaction increases, the intensity of the fission process __________.
increases
decreases
remains the same
none of the above


16: When a radioactive element undergoes an alpha disintegration, both the atomic weight and the atomic number of the daughter nucleus ___________.
increases
decreases
remains the same
none of the above


17: As bismuth 210 emits electrons, the mass of the daughter nuclei formed ____________.
increases
decreases
remains the same
none of the above


18: When uranium 238 changes into plutonium in an atomic reactor, the number of neutrons in atomic nuclei _____________.
increases
decreases
remains the same
none of the above


19: During fission of uranium 235 in an atomic bomb, the number of neutrons ______________.
increases
decreases
remains the same
Answer 4


20: As fusion occurs in the sun, the number of atoms of helium in the sun _______________.
increases
decreases
remains the same
none of the above

2007-12-27 13:12:55 · 5 answers · asked by Ashley G 1

I thought at first that it might be acetate and water but then the nitrogen doesnt show up in the product. I also found someone with a yahoo answer with the equation but it had a hydroxide attatched to the ammonia, is there supposed to be?

2007-12-27 12:52:31 · 6 answers · asked by Kyle P 2

2007-12-27 12:44:27 · 6 answers · asked by Anonymous

2007-12-27 11:58:08 · 4 answers · asked by Ika K 1

2007-12-27 09:25:38 · 2 answers · asked by Anonymous

Can you tell me the product of the following reactions; with a balanced equation?

Al (s) + NaOH ------->

Al2O3 +NaOH -------->

thank you!

2007-12-27 07:59:05 · 3 answers · asked by a a 2

2007-12-27 07:35:08 · 3 answers · asked by Anonymous

I am testing exposure guidelines for a new air coolant.

I run millions of dollars of tight experiments and conclude that the chemical is safe at two different toxicity levels in rats, rat livers and human livers.

I re-run the experiment using rabbits at the lowest toxicity level only...and I've lost 14 of the 48 bunnies already.

On day one, the rabbits appear fine.
By day two, they drop a considerable amount of weight.
By day three, they are emaciated and pass.

What are some possible reasons why my rabbits would die and not my rats?

If the rabbits are dying, but not the rats...how could I determine if this chemical is safe?

2007-12-27 07:32:22 · 6 answers · asked by LUCKY3 6

So many tons of beets are left in the fields each year. It's such a waste! If they (Brazil) can make ethanol out of sugar cane , why can't we use sugar beets? Is our technology so far behind them?

2007-12-27 06:42:38 · 4 answers · asked by Anonymous

2007-12-27 06:31:58 · 3 answers · asked by Anonymous

Ya know, so I can finally be like Wolverine?

2007-12-27 06:17:44 · 6 answers · asked by Anonymous

2007-12-27 05:56:57 · 1 answers · asked by Amanda B 1

an element is in group 15. the last electron added to an atom of this element will be in a (n)____ sublevel
1.s
2.p
3.c
4.f

transition elements have final electrons in the _____ sublevel.
1.s
2.p
3.d
4.f

an element is most likely to have properties similar to those of_____.

1.another element in the same period
2.another element in the same group
3.a noble gas
4.a transition element

what are the valence electrons in the electron configuration of tin, [Kr]4d¹º5s²5p²?
1.[Kr]
2.4d¹º
3.5s²5p²
4.5p²

Ionic radii____down a group in the periodic table.
1.increase
2.decrease
3.stay the same
4.follow no pattern

a metallic ion is____its corresponding atom.
1.larger than
2.smaller than
3.the same size as
4.impossible to compare with

transition elements, such as chromium, are likely to have_____.
1.an oxidation number of 1+
2.an oxidation number of 2+
3.multiple oxidation numbers
4.a negative oxidation number

2007-12-27 05:17:58 · 3 answers · asked by Kracker 2

that will occur in acid solution with all soluble substances present in 1M concentrations. Complere and balance the equation for each reaction that is predicted to occur;
a) H2O2 + Cu'2+ --> Cu + O2
b) H2O2 + Ag'+ --> Ag + O2
c) Ag'+ + Fe'2+ --> Ag + Fe'3+
d) Au + Cl2 --> Au'3+ + Cl'-

2007-12-27 05:06:12 · 1 answers · asked by igizem_2000 1

W is an element from group 1. Predict the chemical reaction of W with:
a) water,
b) oxygen,
state the observation and write the chemical equation involve.

2007-12-27 04:03:02 · 6 answers · asked by James 2

2007-12-27 02:40:06 · 1 answers · asked by Tr4ck4Inc@ 2

2007-12-27 02:31:10 · 2 answers · asked by Anonymous

CH3COOH + NaOH ____NaC2H3O +H2O

2007-12-27 01:21:27 · 8 answers · asked by Buttrefly-Beauty 2

Please answer me !!!!

2007-12-27 01:13:28 · 2 answers · asked by chemistry boy 1

Im having trouble finding them when its for my project. Help me out and send something quick.

2007-12-26 20:12:25 · 0 answers · asked by Anonymous

i am melting 3 salts with different melting point ,they r accumulated in different layer of same bottel .i had given temp higher temp than melting point of 3 salts.i just want to know whether they mix r not

2007-12-26 17:34:11 · 6 answers · asked by sonali 1

My teacher posted our original scores on Powerschool and I was shocked to find out how unfair NYS regent system curve down students' scores in the 90s.
I worked hard to achieve an A on the Chemistry Regent.

2007-12-26 14:26:35 · 2 answers · asked by Jean C 2

I have no use for this small capsule but I know that it has highly compressed carbon dioxide inside of it. I know that it is not flammable and it is non-toxic and it is also all around us but what can I possibly do to blow it up?

2007-12-26 13:37:18 · 3 answers · asked by vp_nyc 2

any help would be appreciated.

2007-12-26 12:30:29 · 2 answers · asked by Anonymous

Which one of the following molecules has a dipole moment?
a. BeCl2
b. Br2
c. BF3
d. IBr
e. CO2

2007-12-26 11:56:58 · 4 answers · asked by Anonymous

Complete this sentence: The PCl5 molecule has ________.
a. nonpolar bonds and is a nonpolar molecule
b. nonpolar bonds but is a polar molecule
c. polar bonds and is a polar molecule
d. polar bonds but is a nonpolar molecule

2007-12-26 11:56:34 · 5 answers · asked by Anonymous

Which one of the following molecules is nonpolar?
a. NH3
b. OF2
c. CH3Cl
d. H2O
e. BeCl2

2007-12-26 11:56:06 · 5 answers · asked by Anonymous

alkali metal carbonate
don't decompose by heating but do they melt or sodiumcarbonate only?

2007-12-26 11:51:42 · 4 answers · asked by roody16 1

According to the VSEPR theory, which one of the following species should be linear?
a. H2S
b. HCN
c. BF3
d. H2CO
e. SO2

2007-12-26 11:50:57 · 4 answers · asked by Charlie W 1

Use bond energies to estimate the enthalpy of formation of HBr(g).

H2(g) + Br2(g) 2HBr(g)

BE(H—H) = 436 kJ/mol
BE(Br—Br) = 192 kJ/mol
BE(H—Br) = 366 kJ/mol
a. +262 kJ
b. –52 kJ
c. –104 kJ
d. +104 kJ
e. +52 kJ

2007-12-26 11:48:44 · 1 answers · asked by Charlie W 1