Science
Almost all metals combine with oxygen to form metal oxides. Metal oxides are generally basic in nature. But some metal oxides show both basic as well as acidic behaviour. Different metals show different reactivities towards oxygen. Some react vigorously while some do not react at all.
(a) What happens when copper is heated in air ? (Give the equation of the reaction involved).
(b) Why are some metal oxides categorized as amphoteric ? Give one example.
(c) Complete the following equations :
(i) Na2O(s) + H2O(l) ⟶
(ii) Al2O3 + 2NaOH ⟶
OR
(c) On burning Sulphur in oxygen a colourless gas is produced.
(i) Write chemical equation for the reaction.
(ii) Name the gas formed.
(iii) State the nature of the gas.
(iv) What will be the action of this on a dry litmus paper ?
Related Questions
In order to trace the inheritance of traits Mendel crossed pea plants having one contrasting character or a pair of contrasting characters. When he crossed pea plants having round and yellow seeds with pea plants having wrinkled and green seeds, he observed that no plants with wrinkled and green seeds were obtained in the F1 generation. When the F1 generation pea plants were cross-bred by self-pollination, the F2 generation had seeds with different combinations of shape and colour also.
(a) Write any two pairs of contrasting characteristics of pea plant used by Mendel other than those mentioned above.
(b) Differentiate between dominant and recessive traits.
(c) State the ratio of the combinations observed in the seeds of F2 generation (in the above case). What do you interpret from this result ?
OR
(c) Given below is a cross between a pure violet flowered pea plant (V) and a pure white flowered pea plant (v). Diagrammatically explain what type of progeny is obtained in F1 generation and F2 generation :
Pure violet flowered plant (VV) x Pure white flowered plant (vv)
Hold a concave mirror in your hand and direct its reflecting surface towards the sun. Direct the light reflected by the mirror on to a white card-board held close to the mirror. Move the card-board back and forth gradually until you find a bright, sharp spot of light on the board. This spot of light is the image of the sun on the sheet of paper; which is also termed as 'Principal Focus' of the concave mirror.
(a) List two applications of concave mirror.
(b) If the distance between the mirror and the principal focus is 15 cm, find the radius of curvature of the mirror.
(c) Draw a ray diagram to show the type of image formed when an object is placed between pole and focus of a concave mirror.
OR
(c) An object 10 cm in size is placed at 100 cm in front of a concave mirror. If its image is formed at the same point where the object is located, find :
(i) focal length of the mirror, and
(ii) magnification of the image formed with sign as per Cartesian sign convention.