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A mineral contains 14.7% calcium and tungsten the remainder is oxygen find its emperical formula
An intrinsic semiconductor has
1. a large number of impurities
2. an excess of electrons
3. an excess of holes
4. none of the above
5. all of the above
A trivalent atom is also called
1. a metal
2. a semiconductor
3. a donor
4. an acceptor
5. None of the above
The valence electron of a copper atom experiences what kind of attraction toward the
nucleus?
1. Strong
2. Weak
3. None
4. impossible to say
5. All of the above
What is the maximum number of electrons that can exist in the shell closest to the
nucleus of an atom?
1. 1
2. 2
3. 4
4. 8
5. 3
The isotopes of magnesium, 24Mg and 25Mg, both form ions with charge 2+. Which of
12 12
the following statements about these ions is true?
A Both ions have electronic configuration 1s2 2s2 2p6 3s2
B 25Mg2+ has more protons than 24Mg2+. 12 12
C The ions have the same number of electrons but different numbers of neutrons.
D The ions have the same number of neutrons but different numbers of protons.
a. A proton NMR spectra that contained some impurities
b. IR, 1H and 13C NMR spectrums of the compound
c. A UV spectra that confirmed the theoretical melting point
d. A perfect 1H NMR spectrum.
Calculate the concentration of ethanol in a sample of wine in %v/v if the wine is found to contain 0.0056 moles of ethanol in a 4.00mL sample of wine and the density of ethanol is 0.785gmL-1.
RCOOR' + H2O RCOOH + R'OH
organomagnesium reacts with carbonyl compounds,
cyanogen chloride, halogenated compounds and alkyl
chloroformate ? Explain with mechanism in each case.
Draw the structure of (2Z,5Z)-3bromohepta-2,5-diene
