Biology; Chemistry; Physics: Post your doubts here!

[exploded diper]

Guys what exactly is a half-life? For example if I have a bag containing a piece of a radioactive element which has 10,000 atoms in it. It's half life is say, 10 minutes. So what would happen after 10 minutes? The number of atoms in the bag will be reduced to 5000 atoms OR the nuclei of those 10,000 atoms contains half the original number of alpha, beta and gama rays?

the atoms will decay and reduce to 5000..approx....

 

[funky brat]

the atoms will decay and reduce to 5000..approx....

Oh alright. Thanks.

 

[Awesome12]

Guys what exactly is a half-life? For example if I have a bag containing a piece of a radioactive element which has 10,000 atoms in it. It's half life is say, 10 minutes. So what would happen after 10 minutes? The number of atoms in the bag will be reduced to 5000 atoms OR the nuclei of those 10,000 atoms contains half the original number of alpha, beta and gama rays?

Half life is the time taken for half the no. of nuclei in a given sample to decay

 

[exploded diper]

dude.....just answer me post....

 

[Awesome12]

dude.....just answer me post....

Which post? The one above mine?

 

[Awesome12]

How is the answer C?

 

[funky brat]

How is the answer C?
View attachment 40011

You're missing the word 'solution'. Since the reaction is limited by the amount of Calcium so the same amount of hydrogen will be produced and there will be excess water in the product.

 

[Awesome12]

You're missing the word 'solution'. Since the reaction is limited by the amount of Calcium so the same amount of hydrogen will be produced and there will be excess water in the product.

Thanks, but when i calculated the mass of calcium hydroxide using moles of Ca, i got 74. What did i do wrong there?

 

[exploded diper]

You're missing the word 'solution'. Since the reaction is limited by the amount of Calcium so the same amount of hydrogen will be produced and there will be excess water in the product.

explain plz......

 

[exploded diper]

Which post? The one above mine?

nitrogen cycle....

 

[Awesome12]

nitrogen cycle....

I have to study that myself

 

[Dark Destination]

Thanks, but when i calculated the mass of calcium hydroxide using moles of Ca, i got 74. What did i do wrong there?

You have to add 64g of water and 74g of Calcium hydroxide as water is in excess.

 

[Karim Nabil]

nitrogen cycle....

here is a link i think it will helps you !
http://www.s-cool.co.uk/gcse/biology/environment/revise-it/cycling-through-nature

 

[Awesome12]

You have to add 64g of water and 74g of Calcium hydroxide as water is in excess.

Where did you get 64 g of water from?

 

[Awesome12]

here is a link i think it will helps you !
http://www.s-cool.co.uk/gcse/biology/environment/revise-it/cycling-through-nature

Thanks

 

[Karim Nabil]

Thanks

my pleasure!

 

[Awesome12]

Are the ways of improving an experiment's reliability the same as 'ways of improving the accuracy of the experiment'?

 

[asadalam]

How is the answer C?
View attachment 40011

Look at this way.There are 2 products,one is aqeuos ,the other a gas.Since its 1 mole of h2 that escaped total mass that escaped would be 2g.So that would be 140-2=138

 

[asadalam]

Are the ways of improving an experiment's reliability the same as 'ways of improving the accuracy of the experiment'?

I believe there may be some difference,like repeating an experiment would make results reliable,but no exactly accurate,while adding more specific solutions and smaller ranges would make results accurate but not specifically reliable.My 2 cents....

 

[Dark Destination]

Where did you get 64 g of water from?

2 moles of water is 36 g. 100g - 36g=64g?
Subtraction

Even i don't understand this question properly, but C would be my tukka.