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To which dimsion ofplantae do algae belong ? Write one characteristic of the division. Give two examples
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1
|
1399
|
June 30, 2016
|
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List the basic criteria for classifying the plantae into various groups. Identify the following specimen given and write its characteristic features
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1
|
1257
|
June 30, 2016
|
|
A student enters the museum and observes the animal specimens. He looks at the one marked whale and calls it a type offish. How will you explain to him that whale and fishes belong to two different classes ? List any three distinguishing features to justi
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1
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1434
|
June 30, 2016
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(a) In which two ways are amphibians differed from fishes ? (b) Identify the phylum of organisms having the following characteristics. (i) Pore bearing animals and radial symmetry. (ii) Body spiny and radial symmetry
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1
|
1958
|
June 30, 2016
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|
Classify the following organisms based on the absence / presence of true coelom i.e., acoelomate, pseudocoelomate and coelomate:
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1
|
2491
|
June 30, 2016
|
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Name the phylum to which this organism belongs. Write any two characteristic features of the phylum
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1
|
2944
|
June 30, 2016
|
|
Answer the following in one line or one word: (a) Who discovered neutron ? (b) On the basis of Thomson's model of an atom, explain how the atom is neutral as a whole
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1
|
733
|
June 30, 2016
|
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(a) Which popular experiment is shown in the figure ? (b) List three observations of this experiment. (c) State conclusions drawn from each observation of this experiment. (d) State the model of atom suggested on the basis of the above experiment
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1
|
9008
|
June 30, 2016
|
|
(a) (i) Name the Scientist who proposed this model of atom. (ii) Write the three postulates of this model. (iii) How many maximum electrons can be accommodated in M orbit ? (b) What are canal rays ? Give the characteristics of canal rays
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1
|
2095
|
June 30, 2016
|
|
Give reasons for the following: (a) In potassium and calcium, the filling of electrons in the N-shell starts after M-shell has acquired 8 electrons although M-shell can accommodate upto 18 electrons. Why?
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1
|
3304
|
June 30, 2016
|
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A) What are isobars ? (b) Atomic number of an element Y is 17
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1
|
4920
|
June 30, 2016
|
|
Explain why did Rutherford select a gold foil in his alpha scattering experiments ? (b) What observations in a-scattering experiment led Rutherford to make thefollouring observations:
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1
|
2495
|
June 30, 2016
|
|
Sulphur dioxide (S02) is a colourless pungent smelling gas and is a major air pollutant. (a) Write the electronic configuration of its constituent elements 'sulphur and oxygen'. (b) Write valency of sulphur and oxygen
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1
|
1790
|
June 30, 2016
|
|
Rutherford designed an experiment to determine the structure of an atom. Answer the following in relation to this experiment: (a) Name the element he selected for this purpose. (b) Which subatomic particle were used by him?
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1
|
1001
|
June 30, 2016
|
|
The average atomic mass of a sample of an element y is 35.5u. What are the percentages of isotopes in the sample
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1
|
2697
|
June 30, 2016
|
|
A) Describe the main features of Bohr's model of an atom. Draw a neat and labelled diagram of energy levels. (b) Which of the following pairs are isotopes and which are isobars?
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1
|
14420
|
June 30, 2016
|
|
(a) 12 Mg and Mg are symbols of two isotopes of magnesium. Compare atoms of these isotopes with respect to: (i) composition of their nuclei. (ii) electronic configuration and valency
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1
|
3002
|
June 30, 2016
|
|
Given that natural sample of iron has isotopes Fe,Fe and Fe in the ratio of 5%, 90% and 5% respectively. What will be the average atomic mass of iron (Fe)?
|
|
1
|
3092
|
June 30, 2016
|
|
The following data represents the distribution of electrons, protons and neutrons in atoms of four elements A, B, C, D
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1
|
11905
|
June 30, 2016
|
|
(a) Calculate the mass of 0.5 mole of sulphuric acid. Atomic mass (H = 1 u, S = 32 u, O = 16 u). (b) Find the number of atoms in 12 g of carbon. (c) How many atoms are present in (i) H2S molecule (ii) PO4 3- ions. (d) Write the names of elements present
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1
|
5955
|
June 30, 2016
|
|
(a) Write the chemical symbols of two elements : (i) which are formed from the first letter of the elements name. (ii) whose name has been taken from the names of the elements in Latin. (b) Define Avogadro's constant and molar mass
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1
|
9097
|
June 30, 2016
|
|
What do the following formulae stand for : (i) 2O (ii) O2 (iii) O3 (iv) H2O (b) Give the chemical formulae of the following compounds : (i) Potassium carbonate (ii) Calcium chloride (c) Calculate the formula unit mass of Al2(SO4)3
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|
1
|
4821
|
June 30, 2016
|