How many atoms of lead are there in 10.0 g of lead?

2.9 ×10^22 atoms of lead.

Explanation:

Now, we have to make use of the Avogadro's number. Remember that according to professor Avogadro, the mole refers to the amount of substance that contains the same number of elementary entities as 12 grams of carbon-12.

The number of elementary particles (atoms, ions, molecules etc) present is one mole of a substance is equal to the Avogadro's number. Hence one mole of a substance contains Avogadro's number of elementary entities.

Now one mole of lead has a mass of 207.2 gmol-1. One mole of lead contains 6.02×10^23 atoms (Avogadro's number) of atoms.

Hence if 207.2 g of lead contains 6.02×10^23 atoms of lead

10.0 g of lead will contain 10.0 × 6.02×10^23 / 207.2 = 2.9 ×10^22 atoms of lead.

Hence 10.0g of lead contains 2.9 ×10^22 atoms of lead.

The number of atoms  in 10 g of Pb is 2.9064 × 10²² atoms

Explanation:

According to Avogadro's constant, one mole of a substance contains exactly 6.02214076 × 10²³ particles such as molecules, atoms or ions.

Here we have lead, Pb, which is an uncombined element, therefore, the number of moles present in 10 g of lead can be found as follows;  

Molar mass of lead = 207.2 g/mol

Mass of lead sample = 10 g

Therefore, number of atoms in 10 g of lead is found by multiplying the number of moles by the Avogadro's number as follows;

Number of atoms = Number of moles × Avogadro's number

∴ Number of atoms  in 10 g of Pb = 0.04826 × 6.02214076 × 10²³ = 2.9064 × 10²² atoms.

The number of atoms  in 10 g of Pb = 2.9064 × 10²² atoms.

hydrocarbons are organic compounds that contain only hydrogens and carbons. they can be saturated (those which contain only carbon-carbon single bonds) or unsaturated (those which contain carbon-carbon double or triple bonds) in nature. hydrocarbons can undergo several reactions like substitution, elimination etc.  

on substituting one or more hydrogen atoms in hydrocarbon it results in the formation of haloalkane. as the halogen atoms are large compared to the carbon and hydrogen atoms, due to which the molecular weight increases and the bond become polar because of presence electronegative halogen atom and results in the increase in boiling point of the haloalkane.

thus, the correct option is (b) that is the boiling point of the new compound increases on substituting a hydrogen atom with a halogen in a hydrocarbon.

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.