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Answer:
dear i am answering these in short
25.
1)because aluminium oxide reacts with both acids and bases.
(then you could write two chemical equations of reaction of AlO2 with acid and base.)
2)when an iron nail is dipped in copper sulphate solution then more reactive iron displaces less reactive copper from its solution to change the colour of blue copper sulphate into green iron sulphate.
(you could write the chemical eqn of reaction of iron with copper sulphate)
3)nitric acid is strong oxidising agent so when it reacts with metals then it oxidises H2 into water and itself reduces to oxides of nitrogen.
4)calcium is a highly reactive metal hence is not found in free state in nature.
5)sodium or potassium vigorously reacts with air hence to avoid the contact of air with these metals these metals are stored under kerosene.
26.
1)compound D
2)compound B is ethanoic acid
CH3-COOH
3)compound C is ethanol
H2SO4 acts as a dehydrating agent
C2H5OH _H2SO4________> C2H4 + H2O
443 K
4)When ethanoic acid and ethanol reacts in presence of H2SO4 then it forms ester and water.
C2H5OH+CH3COOH --H2SO4--------------> CH3COOC2H5 +H2O
the compound formed in product is known as ethyl ethanoate or ester.and the reaction is called esterification reaction.
ester is commonly used in perfumes and flavouring agents.
27.
1)oxygenated blood> pulmonary vein and aorta
deoxygenated blood> pulmonary artery and vena cava
2) double circulation means that blood goes twice to the heart in one complete circulation. once deoxygenated blood goes to lungs and after being oxygenated comes to heart this is called pulmonary circulation. and then from heart blood goes to the whole body and then returns to the heart this is called systemic circulation.
(for flow chart you could prefer the schematic diagram given in your ncert of page 106 figure 6.1)
28.
1)for diagram of binary fission in amoeba you should prefer ncert page 129
during binary fission of amoeba two type of division take place
a)cytoplasmic division
in it the cytoplasm starts to elongate and start dividing into two parts.
b)nuclear division
in it nucleus of amoeba starts dividing and splits into two individuals.
these two divisions led to the binary fission in amoeba.
2) the bodies of multicellular organisms cannot reproduce by the methods by which simple organisms can because in multicellular organisms there many types of cellls are present for various functions in various region.
(you could get this answer as the answer of question of one of your ncert intex question)
dear ask for any doubt
if you want any equation or diagram from me then you could ask for that