Answer:
The use of phenol (carbolic acid) as a wound disinfectant was first practiced by Lister. The correct option is E
Explanation:
Phenol( carbolic acid) is an aromatic organic compound. It has the following properties:
- it's soluble in water
- it's a weak acid and
- highly reactive toward electrophilic aromatic substitution
In Medical field, phenol was first used as an antiseptic by Joseph Lister.Joseph Lister was a student at University College London under Robert Liston, later rising to the rank of Surgeon at Glasgow Royal Infirmary. He believed that patients who passed through surgery, died due to infections caused by microorganisms.He theorized that if germs could be killed or prevented, no infection would occur. Lister reasoned that a chemical could be used to destroy the micro-organisms that cause infection. He made use of the carbolic acid by soaking a clean cloth in them, and placing it over the surgical wounds of patients.
Answer:
D. chlorine, oxygen, nitrogen, hydrogen.
Explanation:
- Thomas Graham found that, at a constant temperature and pressure the rates of effusion of various gases are inversely proportional to the square root of their masses.
<em>ν ∝ 1/√M</em>
where ν is the rate of effusion and M is the atomic or molecular mass of the gas particles.
- The molecular mass for the listed gases are:
O₂: 32.0 g/mol,
Cl₂: 70.906 g/mol,
N₂: 28.0 g/mol,
H₂: 2.0 g/mol.
- Hence, the smallest molecular mass of the gas, the fastest rate of effusion.
So, the order from the slowest to the fastest rate of effusion is:
<em>Chlorine, oxygen, nitrogen, hydrogen.</em>
Answer:
B
as the flows along the outside edge of a curve it removes rock and soil from the river bank