The human hand , cat paw and horse foot when studied in detail show show the same structure of ones and point towards a common origin.
i. What do you conclude from this?
ii. What is the term given to such structures?

There is a pair of bean-shaped organs 'P' in the human body towards the back, just above the waist. A waste product 'Q formed by the decomposition of unused proteins in liver is brought into organ 'P' through blood by an artery "R". The numerous tiny filters 'S' present in organ 'P' clean the dirty blood goes into circulation through a vein ‘T'. The waste substance 'Q' and other waste salts and excess water form a yellowish liquid 'U' which goes from organ 'P' into a bag like structure 'V' through two tubes 'W'. This liquid is then thrown out of the body through a tube 'X'. What is (i) organ P and (ii) waste substance Q.

Covalent molecules formed by heteroatoms bound to have some ionic character. The ionic character is due to shifting of the electron pair towards A or B in the molecule AB. Hence, atoms acquire small and equal charge but opposite in sign. Such a bond which has some ionic character is described as polar covalent bond. Polar covalent molecules can exhibit dipole moment. Dipole moment is equal to the product of charge separation, q and the bond length, d for the bond. The unit of dipole moment is Debye. One Debye is equal to 10^(-18) esu cm. Dipole moment is a vector quantity. It has both magnitude and direction. Hence, dipole moment of molecules depends upon the relative orientation of the bond dipoles, but not on the polarity of bonds alone. A symmetrical structure shows zero dipole moment. Thus, dipole moments help to predict the geometry of the molecules. Dipole moment values can be used to distinguish between cis-and traps-isomers, ortho-, meta-and para-forms of a substance, etc. The percentage of ionic character of a bond can be calculated by the application of the following formula : % " ionic character " = ("Experimental value of dipole moment ")/("Theoretical value of dipole moment ") xx 100 Arrange the following compounds in increasing order of dipole moments, toluene (I), o- dichlorobenzene (II), m-dicblorobenzene (III) and p dichlorobenzene (IV) :

Covalent molecules formed by heteroatoms bound to have some ionic character. The ionic character is due to shifting of the electron pair towards A or B in the molecule AB. Hence, atoms acquire small and equal charge but opposite in sign. Such a bond which has some ionic character is described as polar covalent bond. Polar covalent molecules can exhibit dipole moment. Dipole moment is equal to the product of charge separation, q and the bond length, d for the bond. The unit of dipole moment is Debye. One Debye is equal to 10^(-18) esu cm. Dipole moment is a vector quantity. It has both magnitude and direction. Hence, dipole moment of molecules depends upon the relative orientation of the bond dipoles, but not on the polarity of bonds alone. A symmetrical structure shows zero dipole moment. Thus, dipole moments help to predict the geometry of the molecules. Dipole moment values can be used to distinguish between cis-and traps-isomers, ortho-, meta-and para-forms of a substance, etc. The percentage of ionic character of a bond can be calculated by the application of the following formula : % " ionic character " = ("Experimental value of dipole moment ")/("Theoretical value of dipole moment ") xx 100 A diatomic molecule has a dipole moment of 1.2 D. If the bond length is 1.0 xx 10^(-8) cm, what fraction of charge does exist on each atom?

(i) A pair of dice are rolled. What is the probability that they sum to 7 given that neither die shows a 2 ? (ii) A pair of dice is thrown. Find the probability that either of the dice shows 2 when their sum is 6.

Answer in one word or one line. (i) Give the common name of Periplaneta americana. (ii) How many spermathecae are found in earthworm? (iii) What is the position of ovaries in the cockroach? (iv) How many segments are present in the abdomen of cockroach? (v) Where do you find malphigian tubules?

There is a pair of bean-shaped organs 'P' in the human body towards the back, just above the waist. A waste product 'Q' formed by the decomposition of unused proteins in liver is brought into organ 'P' through blood by an artery 'R'. The numerous tiny. filters 'S' present in organ 'P' clean the dirty blood goes into circulation through a vein 'T'. The waste substance 'Q' other waste salts and excess water form a yellowish liquid 'U' which goes from organ 'P' into a bag like structure 'V' through two tubes 'W' and 'X'. This liquid is then thrown out of the body through a tube 'X'. What is (i) organ P and (ii) waste substance Q ?

D(+) Glucose has melting point 140^(@)C and specific rotation [a]_(D)^(25) is 112^(@)C . Another D(+) Glucose has melting point 150^(@)C and specific rotation [a]_(D)^(25) is +18.7^(@)C . The two form have significantly different optical rotation but when an aqueous solution of either form is allowed to stand, it rotation changes. The specific rotation of one form decreases and rotation of other increases until both solution show the same value +52.7^(@) . The change in rotation towards an equilibrium value is called mutarotation [alpha]_(D)^(25) = +18.7^(@)C " " [alpha]_(D)^(25) = +112^(@)C What percentage of beta-D-(+) glucopyranose found at equilibrium in the aqueous solution?