Important Questions of class 12 Biology

Important Questions of class 12 Biology . check out chapter wise important questions based on new pattern of CBSE . http://bit.ly/2pxgpCz

Comments

Post a Comment

Popular posts from this blog

CHEMICAL PROPERTIES OF CARBON FAMILY

CHEMICAL PROPERTIES OF CARBON FAMILY  (1)        Reactivity towards acids : C, Si, Ge unaffected by dilute acid but Sn dissolves in dilute HNO 3   forming Sn(NO 3 ) 2 . Pb dissolves slowly in dilute HCl forming PbCl 2   and quite readily in dilute HNO 3   forming Pb(NO 3 ) 2   and oxides of nitrogen.             Si is oxidised and undergoes fluorination by hot concentrated HF/HNO 3 .             Sn dissolves in several concentrated acids. Pb does not dissolves in concentrated HCl because a surface coating of PbCl 2   is formed. (2)       Reactivity towards alkalies : Carbon is unaffected by alkalies. Si reacts slowly with cold aqueous solution of NaOH and readily with hot NaOH solution giving solution of silicates [SiO 4 ] 4– . Sn and Pb are amphoteric it dissolve...
Read more

Trigonometry Table

Image
Trigonometry The Word 'trigonometry' is derived from the Greek words 'tri' (meaning tree), 'gon' (meaning sides) and 'metron' (meaning measure). In fact trigonometry is the study of relationship between the sides and angle o the triangle. In This chapter, we will study some ration of the sides of a right triangle with respect to its acute angles, called trigonometric ratios of the angle. We will restrict our discussion to acute angle only. However, these ratios can be extended to other angles also. We will also define the trigonometric rations for angles of measure 0 o and 90 o . We will calculate trigonometric ratios for some specific angles and establish some identities involving these rations, called trigonometric identities. Trigonometricration Let us take a right triangle ABC as shown in Here   CAB (or, in brief, angle A) is an acute angle. Note the position of the side BC with respect to angle A. If faces   A. we ca...
Read more

Silicates Notes for class 11 Chemistry

class 11 chemistry Notes Silicates Binary compounds of silicon with oxygen are called silicates but they contain other metals also in their structures. (i)              Since the electronegativity difference between O & Si is about 1.7, so Si–O bond can be considered 50% ionic & 50% covalent. (ii)            If we calculate the radius ratio then,r Si 4+ /r O 2- = 0.29 It suggests that the coordination number of silicon must be 4 and from VBT point of view we can say that Si is sp 3   hybridized. Therefore silicate structures must be based upon SiO 4 4–   tetrahedral units. (iii)       SiO 4 4–   tetrahedral units may exist as discrete units or may polymerise into larger units by sharing corners.         ...
Read more