what is a radical ???

what is the difference beetween celcius and centigrade.if yes then why and if no then why are the known with two different names?

in my school book it has been given that phenopthalein looks pink in colour in neutral state and in alkaline state.so how can we know that in which state it is as it is pink in clour in both states.

name the following;

a base which reacts with an acid to give a salt which on hydrolsis gives a slightly acidic solution. 

what effect does the concentration of hydronium ion have on solution?

do basic solution also have h⁺(aq)?why are they called basic?

how we can obtain base from other base

Why is the solution of Ferric chloride acidic in nature?

plz explain what are soluble and insoluble salt?also explain solubility  of salt taking in factor temperature.give examples

 does the type of salt  produced when base react with metal is different from salt produced in case when metal react with acid

does this reaction are  reversible.plz explain both the question answer

 plz explain preparation of acid

 mam actually metal react with basic oxideor hydroxide to give metal salt and water but here it is written that they react with metal oxdie

they are neutralistion reaction

 reaction of HNO3 with copper turnings.

1.  A Metal oxide soluble in excess caustic soda.
2. A metal chloride soluble in ammonium hydroxide solution.
3. A salt which gives ammonia gas when heated with NaOH.
4. A lead salt completely soluble in water.

 tomato has which acid.........

 what is :-  (A). Normal salt

 (B).Mixed salt

(C).Double salt

Explain with examples please !!!  :)