Physics, Chemistry and Biology: Post your doubts here!

[princess sofia]

lsn. if my ans comes 3.7 cm in physics atm in a measurement, can we round off to nearest 10? like to 4?

yeah bt we shd always round off at da final ans to get accuracy

 

[princess sofia]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s08_qp_1.pdf
Q15 why isnt it an endothermic reaction , markscheme says ans C how????

 

[avirath]

what is dichotomous key ??

 

[Awesome12]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s05_qp_1.pdf
Q2 why B??
isnt the stop clock wll be used in measuring chane in temp

A stop clock is used to measure changes throughout time. Over here, he is measuring the change in temperature, which can only be measured using a thermometer, and not a stopwatch

 

[Awesome12]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s08_qp_1.pdf
Q15 why isnt it an endothermic reaction , markscheme says ans C how????

This reaction is a neutralization reaction. And all neutralization reactions are exothermic and not endothermic

 

[princess sofia]

This reaction is a neutralization reaction. And all neutralization reactions are exothermic and not endothermic

but there is a rise in temperatre shown wt abt dat

 

[Awesome12]

but there is a rise in temperatre shown wt abt dat

Exothermic reactions are reactions which release heat causing a temp rise in the surroundings
Endothermic reactions are reactions which absorb heat from the surroundings, causing a temp drop in the surroundings

 

[princess sofia]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s07_qp_6.pdf
Q5 part h
how do we know it was barium sulphate formed whn barium chloride also gives white ppt ????????????

 

[Awesome12]

http://papers.xtremepapers.com/CIE/Cambridge IGCSE/Chemistry (0620)/0620_s07_qp_6.pdf
Q5 part h
how do we know it was barium sulphate formed whn barium chloride also gives white ppt ????????????

but there is no reference to barium
have you posted the correct link?

 

[princess sofia]

but there is no reference to barium
have you posted the correct link?

in the table part e (i) it says dat they added barium nitrate

 

[asimkhanfar]

A

what is dichotomous key ??

dichotomous key is a key which is used to identify an organism from a group of unknown organisms by visible characteristics
It always branches into two

For example : more than 4 legs, go to 2
4 legs or less, go to 3

 

[asimkhanfar]

What's an acrosome?

An acrosome is an organelle within the human sperm cell (not sure about other organisms) that contains enzymes for fertilization when it reaches the egg to digest a pathway to the haploid nucleus

 

[Phoenix Blood]

I am having problem with moments. Especially stable,neutral and unstable equilibrium..plx help!!!!!!!!!!

Moment is the turning effect of force.
An object is in stable equilibrium when it doesn't turn.
An object is in unstable equilibrium when it is about to turn.
An object is in neutral equilibrium when it is continuously turning.

 

[Phoenix Blood]

Someone help me with Q.10,(b), (i) and (ii)

 

[Lola_sweet]

I am having problem with magnetism, forces and moments. Can anyone give me any advice on how to study these topics or any useful resources related to these topics. Thank You!

 

[Awesome12]

Someone help me with Q.10,(b), (i) and (ii)

b (i)
it says that for every 5.0 V applied, the spot covers 1 cm vertically
They have asked the maximum p.d applied which is equivalent to the amplitude of the wave
the amplitude of the wave is 1.5 cm which is
1.5 * 5 =7.5 V

 

[Awesome12]

b (ii)
the wavelength of the wave is 4.0 cm
thus the time taken/ time period is 4.0 ms

since frequency is inversely proportional to time period, the frequency will be
f= 1/0.004
f=250 hertz

 

[Dubi Pro]

b (ii)
the wavelength of the wave is 4.0 cm
thus the time taken/ time period is 4.0 ms

since frequency is inversely proportional to time period, the frequency will be
f= 1/0.004
f=250 hertz

this question man! the 9th one please try to solve this set one! its really tough for me!

 

[Dubi Pro]

b (ii)
the wavelength of the wave is 4.0 cm
thus the time taken/ time period is 4.0 ms

since frequency is inversely proportional to time period, the frequency will be
f= 1/0.004
f=250 hertz

this question man! the 9th one please try to solve this set one! its really tough for me! View attachment 37514

 

[Lola_sweet]

this question man! the 9th one please try to solve this set one! its really tough for me! View attachment 37514

Which paper is this?