Answer:
Only two elements are liquid at standard conditions for temperature and pressure: mercury and bromine. Four more elements have melting points slightly above room temperature: francium, caesium, gallium and rubidium.
Explanation:
How do seed plants protect their embryos?
Reptilian embryos are protected from desiccation by a leathery shell. Similarly, sporophytes of both gymnosperms and angiosperms protect embryos within, and they also protect male gametophytes against desiccation using .....
Answer:
0.80 seconds (2 significant figures)
Explanation:
The equation of the reaction is given as;
CICH2CH2Cl (g) --> CH2CHCI (g) + HCl(g)
Rate constant (k) = 2.01 s^-1
From the units of the rate constant, this is a first order reaction.
Initial Concentration = 1.34 M
t = ?
Final concentration = 20% of 1.34 = 0.268 M
The integrated rate law for a first order reaction is given as;
ln[A] = ln[A]o - kt
ln(0.268) = ln(1.34) - 2.01(t)
-2.01(t) = - 1.6094
t = 0.8007 ≈ 0.80 seconds (2 significant figures)
Answer : Hydrogen-bonding, Dipole-dipole attraction and London-dispersion force.
Explanation :
The given molecule is, 
Three types of inter-molecular forces are present in this molecule which are Hydrogen-bonding, Dipole-dipole attraction and London-dispersion force.
- Hydrogen-bonding : when the partial positive end of hydrogen is bonded with the partial negative end of another molecule like, oxygen, nitrogen, etc.
- Dipole-dipole attraction : When the partial positively charged part of the molecule is interact with the partial negatively charged part of the molecule. For example : In case of HCl.
- London-dispersion force : This force is present in all type of molecule whether it is a polar or non-polar, ionic or covalent. For example : In case of Br-Br , F-F, etc
Hydrogen-bonding is present between the oxygen and hydrogen molecule.
Dipole-dipole forces is present between the carbon and oxygen molecule.
London-dispersion forces is present between the carbon and carbon molecule.
I don't know how well known/accepted this is (it's in my textbook so I'm guessing it's right), but Sulphur has two forms - the alpha and beta forms ,apparently gamma sulphur exists as well.
The alpha form is rhombic, yellow in color and has a MP of 385.8 K. The beta form is colorless and has a MP of 393 K and is formed by melting rhombic sulphur and cooling it till a crust forms on top. Poke a hole and pour out the liquid inside and you get beta sulphur. The transition point is 369K - below it, alpha sulphur is stable and above it, beta sulphur is stable. Both have helped. I had to pull out an old textbook and that's something that I don't usually do.
