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Chemistry Obj

1CCDBCBDBCA
11DBAADCDBCB
21DBCBCCDBAD
31BACBACBCCD
41BDACABDABD

1ai)
an acid base indicator is a weak acid or
weak base that exhibits a colour change
as the concentration of hydrogen (H^+) or
hydroxide (H^-) ions changes in an
aqueous solution
1aii)
methyl-orange
1b)
i)oxidizing agent
ii)mixed anhydride
1c)
enthalpy of combustion is the heat
evolved when one mole of a substance is
completely burns in oxygen gas under
standard conditions
1cii)
enthapy of combustion is always negetive
since it involvs a rise in temperature and
heat of reactants is greater than the heat
of products
1d)
primary cell is a cell that cannot be re
charged while secondary cell is a cell that
can be recharged
1dii)
primary cell — daniell cell
secondary cell — lead accumulator
1e)
mole is the unit of measurement in the
International System of Units (SI) for
amount of substance. The unit is defined
as the amount of a chemical substance
which contains as many representative
particles, e.g., atoms, molecules, ions,
electrons, or photons, as there are atoms
in 12 grams of carbon-12 (12C), the
isotope of carbon with relative atomic
mass
1f)
n= V=40cm^3
c= 0.40moldm^3
n=cv/1000
0.40*40/1000 = 0.016mol
1g)
Carbon or graphite
Plantinum
1h)
– induced dipole – induced dipole
interaction or dispersion force
-dispole- dispole interaction
1i)
– carbon(ii)oxide and water or co and H2O
1j) 26FE³+ — 1s²2s²2p^6 3s²3p^63d³4s²
=====================
2a)
i)periodic law states that properties of
elements are the periodic function of their
atomic number
ii)periodic property of element is the
variation of the properties of element in a
regular pattern both down the group and
acrose the period
2aii)
i)ionization energy
ii)electron affinity
iii)electropositivity
2aiii)
ionization energy increase from left to
right acrose a period because the nuclear
charge increase progressively while the
screening effect remain constant
-atomic reduis decreases from left to right
acrose the period because nuclear charge
effect out weighs screening effect,which
remains constant because the number of
shell in a period is constant
-electron affinity increase from left to
right across a period because an
additional electron will experience a
greater repulsion than altraction from the
positively charged nucleus
2b)
the relative atomic mass of an element is
the mass of one atom of the element
compared with the mass of an atom of
the carbon -12 isotope whos mass is
exactly 12
2bci)
isotopy
2cii)
the isotopes have difference number of
neutron
2ciii)
R.A.M=(75/100*35)+(25/100*37)
=2634.25
2di)
I CO2 by downward delivery
II HCL by downward delivery
III H2 by upward delivery
2dii)
I because it is denser than air
II because it is denser than air
================================
3ai) Thermal cracking
aii) C4H8
aiii) (I) H H. H
| | |
H-C-C-C=C
| | | |
H H H H
and
(II) H H
| |
H-C-C=C-C-H
| | | |
H H H H
aiv) I-normal butene
II -But-2-ene
Ni
av) C4H8 +H2 ——-> C4H10
250c
3 b )
in other words the oil is stained red . This
is a aspecifit test for fats
if suden ( iii ) is added to fats a distinct
red colouration is observed
3 c )
Given 2502 + 02 + 2 H20 – – – >2 H2 SO 4
1 mole produce 2 mole
1 . 3 mole produce 3 mole
moles of H 2 SO 4 = 3 mole
molar mass of H 2 SO 4 = ( 1 + 2 ) + 32 +
( 4 * 16 )
= 2 + 32 + 64
= 98 gmol – ^ 1
mole= mass /molar mass
mass and H 2 SO 4 = Mole* molar mass
= 3 * 98
= 294 g
3 di )
DH 2 < DH 3 < DH 1 ================================ === 5ai) worm the unknown substance with concentrated H2SO4 in a test tube. if trioxonitrate(v) ion's are/is present, some trioxonitrate(v) acid will be condensed as oily drops on the upper part of the tube. On further heating, the acid decomposes yielding brown fums of NO2 gas. 5iia) Sodium chloride is used for: =preserving food =glazing pottery 5iib) Sodium trioxocarbonate(iv) is used for: =standardizing acids in the laboratory =the manufacture of glass 5bi) C(s) + O2(g) =====> Co2(g)
Co2(g) + C(s) =====> 2Co(g)
Fe2O3(s) + 3Co(g) =====> 2Fe(l) +
3Co2(g)
The limestone present decomposes as
follows:
CaCo3(s) =====> CaO(s) + Co2(g)
Which is available to remove silicon(iv)
oxide impurity
SiO2(s) + CaO(s) =====> CaSiO3(s)
5bii) Faraday’s first law of electrolysis
states that, the mass (m) of an element
discharged during an electrolysis is
directly proportional to the quantity of
electricity (Q) passing through it.

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Posted by on April 15, 2017.

Categories: College Of Edu News, Jamb, Polytechnics, Universities

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