Which of the following particles when moving causes electricity?

a hydrogen atom
a proton
an electron --> Answer!!
a hydrogen ion

How do two negative charges interact when they are brought close together?

attract
no interaction
repel
ground


The answer is repel . Because only negative charges interact with positive charges.

Electric charge flows from higher_____to lower.

induction
circuit
voltage --> answer
power

0.5g of zinc powder was found to reduce an acidified solution of 25.50 cm^3 of 0.200 mol/dm^3 AO2^+ . What Is the final oxidation number of metal A . Options : A) 0. B) +1 C) +2. D) +3

0.5 g / 65.409 g/mol = 0.0076442 mol of Zn

Zn ---> Zn2+ + 2e-

0.0076442 mol times2 = 0.0152884 mol of electrons produced

MV = moles

(0.200 mol/L) (0.02550 L ) = 0.0051 mol of AO2^+

0.0152884 mol / 0.0051 mol = 2.998 = 3

In AO2^+, the oxidation number of A is +5. It was reduced by 3 oxidation numbers to +2.

Answer choice C

Balance the following

Cl2 + NaBr -> ?
CaCO3 -> ?
Zn + HCl -> ?
Ca(OH)2 -> ?
H3PO4 + KOH -> ?
AgNO3 + Ha -> ?
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Balanced equations have equal numbers of atoms on each side. The net charge also balances. The number of molecules does not have to be equal.

Cl2 + 2NaBr -> Br2 + 2 NaCl (REDOX : Bromine is reduced by Chlorine)

CaCO3 ->Ca(+2) + CO3(-2) (not very soluble, but these ions form)

Zn + 2HCl ->ZnCl2 + H2 (classic metal + acid = salt and gas)

Ca(OH)2 ->Ca(+2) + 2OH(-) (not very soluble, but these ions form)

(acid + base = salt and water)
H3PO4 + KOH ->KH2PO4 + H2O (Potassium dihydrogen phosphate formed)
H3PO4 + 2KOH ->K2HPO4 + 2H2O (Potassium hydrogen phosphate formed)
H3PO4 + 3KOH ->K3PO4 + 3H2O (Potassium phosphate formed)

AgNO3 + Ha ->Aga + HNO3 ("Ha" is some kind of acid)

You might want to include those silly subscripts like "(g)", "(s)" and "(aq)" which chemnistry teachers are so fond of. Working chemists never use them.

What is the half-life (in years) of 44-Ti if a 1.0 ng sample decays initially at a rate of 4.8x 10^3 disintegrations per second?

1 ng = 1*10^-9 g = 4.8*10^3 Bq 
1 g = 4.8*10^12 Bq 

the specific activity of an isotope is found by
A = ln(2)/T1/2 * N/M

with T1/2 = half life in seconds 
N = Avogadro's constant = 6.022*10^23 atoms/mol
M = molecular mass in g = 44

T1/2 = ln(2)*N/(A*M) 

T1/2 = ln(2)*6.022*10^23/(4.8*10^12*44) 
T = 1.976*10^9 s 

T = 1.976*10^9/(365*24*60^2) years 
= 62.65 years
(Wiki says 49 years though) 

Of the metals Au, Fe, Na and Cd which will not give up its electrons to silver (Ag) in a redox reaction?

Au

Fe

Na

Cd

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Au - because it is less reactive than Ag