An ore contains PbS and ZnS. Sodium cyanide is used as depressant. Which of these sulphide comes with the froth? 

Name the method used for concentration of sulphide ores.

Name the process used for the concentration of sulphide ores.

Carbon cannot be used to reduce the oxide of sodium, magnetsium, calcium, etc.to their respective metals. State the method used for obtaining these metals from their salts. For obtaining sodium from its compound. a. Name the salt used, gas produced, and the electrode at which the metal deposits. b. Show the chemical reaction taking place during the process. c. Name any two other metals which can be obtained from its compounds by the above method.

When food containing fat or oil is not used and left for a long time, their smell and state changes. Name the process which is responsible for this change . List two methods to prevent or slow down the above change.

(i) Define universal indicator. For what purpose it is used? (ii) Two solutions A and B have pH values of 3.0 and 9.5 respectively. Which of these will turn litmus solution from blue to red and which will turn phenolphthalein from colourless to pink? (iii) What is a neutral substance. WHat colour will you get when you add a few drops of universal you get when you add a few drops of universal indicator of a test tube containing distilled water?

Which type of ore is concentrated by froth-floatation?