Recent content by iknownth

For the iodine test, How does boiling alcohol speed up the diffusion of chlorophyll out of the cells? Why does the leaf become crisp and breaks easily after it has been dehydrated by alcohol? For the detection of oxygen produced from photosynthesis, Why does sodium hydrogencarbonate...

Sorry, it should be "4. When metals are burnt, metal oxides(some coloured) are formed".

1. A simple equation for the reaction: 2 KNO3 (aq) + C (s) + S (s) -> K2S (s) + N2 (g) + 3 CO2 (g) The oxidation number of carbon increases from 0 to +4. The oxidation number of nitrogen decreases from +5 to 0. The oxidation number of sulphur decreases from 0 to -2. Are these correct? 2...

"Because brass is not ferromagnetic, it can be separated from ferrous scrap by passing the scrap near a powerful magnet." This sentence seems contradictory. Not ferromagnetic but can be separated near a magnet?? What does it mean??

The website http://www.ehow.com/how_6365159_tell-metal-gold-brass.html mentions that brass is magnetic but here http://uk.answers.yahoo.com/question/index?qid=20070512044233AA5QE4b many say brass is not magnetic. So, is brass magnetic?

How can one prove that sin theta = opposite side / hypotenuse ?

We all know that sin theta = opposite side / hypotenuse cos theta = adjacent side / hypotenuse tan theta = opposite side / adjacent side. But why? Are there some explanations behind or are they just defined by scientists?

The force from S2 to S1 should be double that of the force from S1 to S2 because S2 has charge 2Q??

Two spheres S1 and S2 hang from light insulating strings of the same length from points P1 and P2 which are on the same level. S1 is of mass M and has charge Q. S2 is of mass M and has charge 2Q. Repulsion between S1 and S2 causes their strings to be inclined at angles of theta1 and theta2 to...

Are electrostatic attraction between the positively charged nucleus and the negative electrons and electromagnetic force the same?

But I still don't understand why one would say that insulators have strong covalent bonds inside and so electrons are tightly bounded to the nucleus. How do strong covalent bonds help bind electrons to the nucleus?

"Inside an insulator, the electrons are tightly held by nuclei." What is the force that hold the electrons? I found out from the Internet that insulators have strong covalent bonds inside and so electrons are tightly bounded to the nucleus. But in another source, it is stated that...

Our hands are high in the triboelectric series, which means our hands lose electrons easily. Is there a reason behind?

The balloon becomes positively charged temporarily, then why can steps 3 & 4 of the experiment still be carried out? How do we know if an object becomes positively charged or negatively charged? By the triboelectric series, rubber should be more likely to gain electrons. Should the balloon be...

... These are my questions and I have thought about it for some time. I really don't understand. "The aluminium can is an neutral object and the rubber balloon is positively charged after rubbing with hair. Thus, it can attract the aluminium can." This is what I think is happening here. I just...