IF the solution is diluted, can the path of light be visible?

Direct a beam of light from a torch or a laser beam on the test tubes. Is the path of the light beam visible in the liquid?

At 20^(@)C , the osmotic pressure of urea solution is 400 mm. The solution is diluted and the temperature is raised to 35^(@)C , when the osmotic pressure is found to 105.3 mm. Determine the extent of dilution………

0.1 M HCI solution is diluted by 100 times. The pH of the solution so formed is…………

HCI is labelled as 3.65% (w/v) 10ml of the solution is diluted to 1 lit. The proton concentration in the resulting solution is

The P^(H) of a solution is 3.0. This solution is diluted by 100 times. Then the P^(H) of the resulting solution is

If molality of the dilute solution is doubled, the value of molal depression constant (K_f) will be

Are there any other wavelengths of light other than visible spectrum?