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What determines the strength of the metalic bond? As far as I know, the factors that affect the strength metalic bond includes 1. number of valence electron 2. size of the atom with these knowledge, i still don't understand why mercury is liquid at room temperature. Francium and caesium (cesium) are liquid. I think this is due to large atomic size and single valence electron. Bromine is liquid due to weak Van der waals forces. Galium is liquid at room temperature. What are the reasons? Any help?

Since the 6s1 does not show the relative energy level, what is the significance of the principal number? How energy level n=5 is different from n=6 ? I can understand that 6s1 is not the outer shell so gold and silver are not reactive.

Let $2 and $1 be the determining factor and let $0.50 to mark up the sum to $100. When $2 x 50, $1 x 0 and $ 0.50 x 0~~~~~this is one way When $2 x 49, $1 can be x1 or x2 or x0 and let $0.50 to mark up to the sum Then this will be 3 way. $ 1 x0 would mean than no one dollar is used, only two dollar and 50p will be used. When $2 x 48, $1 can be x1 or x2 or x3 or x4 or x0. Therefore, there are 5 ways .............................. .............................. when $2 x 1, $1 can be x0 or x1 or .... or x 98, a total of 99 ways when $2 x 0, $1 can be x0 or x1 or .... or x 98 or x 99 or x 100, a total of 101 ways As you can see , this is an arithmatic progression. To find possible way to make a sum of $ 100, apply arithmatic summation. It will be 1+3+5+...+101=2601 I don't get answer from the option. Maybe there is some mistake in my calculation? Please kindly point out.

I am not sure what "descared " mean. It is taken from the original question paper. I am thinking how to calculate the possibility of getting a "healthy man" ( i think it includes the homozygous and carrier) in the second marriage?

I have taken the following question from Internation Biology Olympiad. I can't figure out the answer yet. 45 In the European population, about 1 in 2500 people suffers from Cystic Fibrosis, a genetically determined (descared), autosomal disease. Healthy parents have a child suffering from Cystic Fibrosis. The woman remarries a healthy man. What is the chance of a child from this second marriage suffering from Cystic Fibrosis: A 1 : 25 B 1 : 50 C 1 : 100 D 1 : 625

I am wondering how kidney is able to filter out the precipitate?

[Pb2+] = 1.5 x 10-5 mol dm-3 [Pb2+] > 1.0 x 10-9 is lethal Ksp of PbCO3 = 3.3 x 10-14 Volume of blood = 1.7 dm3 ~~~~~~~~~~PbCO3~~~~>> ~~~~~Pb2+ ~~~~+~~~CO32- Initial~~~~~~1.5 x 10~~~~~~~~~~~~y~~~~~~~~~~~ - Changes~~–(1.4999 x 10-5 )~~~–(1.4999 x 10-5 )~~~+(1.4999 x 10-5 ) Equilibrium~~~1.0 x 10-9~~~~ y –(1.4999 x 10-5 ) Ksp = [Pb2+][ CO32-] (1.0 x 10-9 ) (y –1.4999 x 10-5 ) = 3.3 x 10-14 y = 4.7999 x 10-5 no of mole of Na2CO3 = 4.7999 x 10-5 volume of blood Mass of Na2CO3 /106 = 4.7999 x 10-5 1.7 Mass = 8.65 x 10-3 g Is this correct ?