NECO GCE 2022 CHEMISTRY ANSWERS / VERIFIED NECO GCE 2022 SURE ANSWERS.
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(i) KAl(SO₄)₂. 12H₂O
Number of moles of sodium reascted = reacting mass/molar mass
Number of moles of oxygen reacted = (1/4) x Number of sodium
= 1/4 x (3.6/23)
Reacting mass of oxygen = Number of moles x molar mass
= 0.03913 x (16×2)
Air in gaseous form is first passed through caustic soda to remove CO₂. It is compressed and cooled until ut becomes a liquid at -200°C. It is then led to a fractionating column. On distillation, Nitrogen which has a lowet boiling point of -196°C is evolced first leaving behind Oxygen in liquid form. Further heating converts the liquid to a gas at -183°C.
(i) It is used for combustion
(ii) It is used for artificial respiration
This is because room temperature is warmer
(i) Methyl orange
An ion is an atom or molecule which has a net electric charge due to the loss or gain of one or more electrons.
HCl gas doesn’t contain ions
(i) Noble gases: Neon, Helium
(ii) Halogens: Iodine, Fluorine
(iii) Alkaline earth metals: Calcium, Magnesium
Halogens attain stable octet configuration by accepting an electron from donors Group I elements.
A sol is a colloid where solid particles are dispersed in liquid medium.
(i) Acid-base titrations are used to determine the percentage purity of a substance
(ii) Acid-base titrations are important to determine the number of water molecules in a hydrate.
A hydrocarbon is an organic compound composed only of two elements carbon and hydrogen.
They are unsaturated compounds
(i) Decrease in pressure
(ii) Finely divided zinc
(iii) Removal of hydrogen gas
(i) Electrovalent compounds conduct electricity While covalent compounds do not.
(ii) Electrovalent compounds dissolve in polar solvents While covalent compounds dissolve in non-polar solvents.
(i) High melting and boiling points
(ii) Exist mainly as solids at room temperature
(i) Ammonia, NH₃
(ii) Hydrogen chloride gas, HCl
(i) Potassium hexacyanoferrate(II)
(ii) It is a complex salt
(i) Wrought iron
(ii) Cast iron
2H₂ + O₂ →2H₂O
2 : 1 : 2
40cm³ : 20cm³ : 40cm³
(50 – 40) (20 – 20)
= 10cm³ = 0cm³ = 40cm³
Total residual volume = 10 + 40
(i) It is cost effective and requires less manpower as it is tool-based.
(ii) It requires field study to interpret data into useful information
(i) It is a costly affair as the data is incurred from space and through sensors and satellites.
(ii) It reduces manual work and ground field study.
(i) In Telecommunication: Satellite remote sensing have been found to be more useful and relevant in telecommunication. The satellite remote sensing has made it possible for regional, national and international communication without being in direct contact with human beings.
(ii) In Transportation: The availability of high resolution commercial remote sensing has contributed to a revolution to the transport network. The satellite remote sensing is useful to transportation, it helps to improve the trafficability of the roads and also contributed greatly in the movement of aero planes, jets and even seen beyond the bonds of human eye sight.
(i) Inadequate Power
(ii) Inadequate Personnel
(iii) Inadequate Personnel
(iv) Inadequate capital
The texture of a rock is the size, shape, and arrangement of the grains (for sedimentary rocks) or crystals (for igneous and metamorphic rocks. Example includes: basalt, andesite and rhyolite.
The structure of an igneous rock is normally taken to comprise the mutual relationships of mineral or mineral-glass aggregates that have contrasting textures, along with layering, fractures, and other larger-scale features that transect or bound such aggregates.
(iii) Colour: Color index is an indicator of the types of minerals present, and the specific type of rock. The color index of an igneous rock is a measure of the ratio of dark colored, or mafic, minerals to light colored, or felsic, minerals.
– Plutonic rocks are formed when magma cools and solidifies underground.
– It cools at a very slow rate and may take thousands or millions of years to solidify.
– Volcanic rocks are formed from lava that flows on the surface of the Earth and other planets and then cools and solidifies.
– It doesn’t cool at a very slow rate and it doesn’t take thousands or millions of years to solidify.
(i) Weather is the atmospheric over a condition of a place short period (days, weeks, hours, months).
(ii) Weather changes very often.
(iii) Weather cannot be generalized.
(i) Climate is the average condition of a place over a long period of time (35 years).
(ii) Climate does not change very often.
(iii) Climate can be generalized.
CHOOSE ANY BEST (2) OF YOUR CHOICE
Environmental resources means any useful item in the environment or materials and substances that are useful to man.
[PICK ANY FOUR]
(i) Atmospheric resources
(ii) Human resources
(iii) Mineral resources
(iv) Land resources
(v) Vegetation resources.
[PICK ANY TWO]
(i) Forest resources such as timber products provide raw materials for the local industries e.g. furniture industry.
(ii) Forest resources provide herbs for pharmaceutical and herbal industries and clinics. They contribute positively to the health of the people.
(iii) Exportation of forest resources provide government with foreign exchange e.g. export of timber.
(iv) It helps various levels of government to generate revenue from taxes imposed on products and firms involved in the exploitation of forest resources.
(v) Grasslands provide food for livestock which serves as food for man.
(vi) Forest resources provide habitation for wild life and also help to promote tourism e.g. Yankari game reserve in Nigeria etc.