In close packing of N spheres,how many (i)octahedral and (ii)tetrahedral sites are present?

Discuss (i) Close packing in one dimension. (ii) Close packing in two dimensions.

In a cubic close-packed structure of a mixed oxide one-eighth of tetrahedral voids are occupied by divalent ions X^(2+) while one half of the octahedral voids are occupied by trivalent ions Y^(3+) . What is the formula of the compound?

Fill up the blanks in the following paragraph by selecting the correct option. During copulation (coitus) semen is released by the penis into the vagina and is called (i)._____.the ovum released by the ovary is transported to the (ii)._____where (iii).______takes place during fertilisation, a sperm comes in contact with the zona pellucida layer of the ovum and induces changes in the membrane that block the entry of (iv)._____The secretions of the (v)._____help the sperm enter into the cytoplasm of the ovum.

Name the ions which form the close packed structure (along with the type of packing) and the ions which fill the voids (along with the types of voids) in the compounds: (i)NaCl" " (ii)ZnS" "(iii) CaF_(2)

(i) When an AC source is connected to an ideal capacitor. Show that the average power supplied by the source over a complete cycle is zero. (ii) A lamp is connected in series with a capacitor. Predict your observations when the system is connected first across a DC and then an AC source. What happens in each case, if the capacitance of the capacitor is reduced ?

How does an unpolarised light gets polarised, when passed through a polaroid? Two polaroids are set in crossed position. A third polaroid is placed between the two, making an angle with the pass axis of the first polaroid. Write the expression for the intensity of light transmitted from the second polaroid. In what orientations will the transmitted intensity be (i) minimum and (ii) maximum?

A charge of 300 muC experiences a force of 3N when placed in a uniform electric field Fine the potential difference between two points separated by a distance of 1 cm (i) along the electric line of force and (ii) perpendicular to the line of force.

Consider the following statements. (i) Polyspermy may bring about fertilisation of egg by more than one male nucleus or the supernumerary sperms may fertilise other components of embryo sac much as synergids or antipodals. (ii) In angiosperms, pollen tube is normally an unbranched structure which ususally persists after fertilisation. (iii) Intine is the inner, pectocellulosic layer of pollen grain wall which is destroyed during acetolysis. (iv) Exine layer of pollen grain comprises of an outer non-sculptured layer sexine and an inner sculptured layer tectum. Which of the following combinations of above given statements is correct ?

Read the following statements regarding euglenoids and select the incorrect ones. (i) These are mostly freshwater organisms found in stagnant water. (ii) Their body is covered by a protein rich layer called pellicle which makes their body flexible. (iii) They are photosynthetic in the presence of sunlight but become heterotrophs in the absence of sunlight. (iv) They usually prosses two flagella, one long and one short. (v) Euglenoids are multicellular ciliate protists