Biology; Chemistry; Physics: Post your doubts here!

[princess Anu]

Then why she wrote
''b,c
i forget answers quickly '':S?

 

[FLRNAB]

y not 4(b) ?

Gold, Platinum, Silver are lower in reactivity series and will not displace hydrogen from HCL so not all metals react with hcl.

dear i know its answer but i need someone to explain this .... y its A?

Look Again.

 

[kirann]

A
B - Carbonate + Acid --> COz like in beverage
C - Metal + Acid --> Salt + Hydrogen
D - Alcohol + Acid = Ester

is ester a sweet smelling compound?

 

[Maganius]

is ester a sweet smelling compound?

Yes

 

[FLRNAB]

is ester a sweet smelling compound?

Yes.

 

[princess Anu]

View attachment 41616
plz explain asap plz

what is the answer to first question. Is it D OR B in marking scheme?

 

[peacce]

y not 4(b) ?

Because carbonates do react with acids thats y it cant be B

 

[Maganius]

what is the answer to first question. Is it D OR B in marking scheme?

D's the correct answer.

 

[FLRNAB]

what is the answer to first question. Is it D OR B in marking scheme?

D.

Why can't be B?
Gold, Platinum, Silver are lower in reactivity series and will not displace hydrogen from HCL.

 

[kirann]

what is the answer to first question. Is it D OR B in marking scheme?

D

 

[Dark Destination]

D.

Why can't be B?
Gold, Platinum, Silver are lower in reactivity series and will not displace hydrogen from HCL.

So those metals won't dissolve? Is this the property of all acids, or just HCL?
What about HNO3?

 

[princess Anu]

its b,c
yeah maybe i did, i forget things very easily.

then what was this for?

 

[FLRNAB]

So those metals won't dissolve? Is this the property of all acids, or just HCL?
What about HNO3?

All Acids unless question says it's concentrated and copper is reacting.
http://en.wikipedia.org/wiki/Reactivity_series

 

[kirann]

how to calculate the value of x in the formula of hydrated compounds?

 

[FLRNAB]

how to calculate the value of x in the formula of hydrated compounds?

1) Find Total Mr of Formula
2) Find Mr of Salt
3) Subtract Salt Mr from Total
4) Divide the number you get by 18 (Mr of Water)

 

[princess Anu]

how to calculate the value of x in the formula of hydrated compounds?

can u please answer my question that why did you say d,c?
s this answer was for which question ?

 

[Dark Destination]

All Acids unless question says it's concentrated and copper is reacting.
http://en.wikipedia.org/wiki/Reactivity_series

Dilute Nitric acid can react with Copper.

 

[FLRNAB]

Dilute Nitric acid can react with Copper.

Like I said Unless copper is stated.

"Some precious metals, such as pure gold and platinum group metals do not react with nitric acid though pure gold does react with aqua regia, a mixture of concentrated nitric acid and hydrochloric acid"
http://en.wikipedia.org/wiki/Nitric_acid

 

[kirann]

then what was this for?

the previous ones.. i think..!!

 

[Dark Destination]

Like I said Unless copper is stated.

"Some precious metals, such as pure gold and platinum group metals do not react with nitric acid though pure gold does react with aqua regia, a mixture of concentrated nitric acid and hydrochloric acid"
http://en.wikipedia.org/wiki/Nitric_acid

It is an oxidizing acid, according to wikipedia.

Apparently, Oxidizing acids can react with metals that are less reactive.
Like Dilute Nitric Acid, the Nitrate Ions act as the oxidizing agents.

In Concentrated Sulphuric acid, the Sulfate ions act as oxidizing agent, and can even reduce copper to Cu+2.

But why don't Gold and Platinum react? Is it something to do with their metallic bonding?

Copper is a metal too, yet is reacts.