Answer:
Energy decreases and wavelength gets longer.
Explanation:
The energy of a wave is given by :
Where
h is Planck's constant
f is the frequency of the wave
As frequency decreases, the energy of the wave also decreases and wavelength gets longer. Hence, the option is (d).
Answer:
10.5g
Explanation:
First, let us calculate the number of mole of NaHCO3 present in the solution. This is illustrated below:
Volume = 250mL = 250/1000 = 0.25L
Molarity = 0.5M
Mole =?
Molarity = mole /Volume
Mole = Molarity x Volume
Mole = 0.5 x 0.25
Mole = 0.125 mole
Now, we shall be converting 0.125 mole of NaHCO3 to grams to obtain the desired result. This can be achieved by doing the following:
Molar Mass of NaHCO3 = 23 + 1 + 12 +(16x3) = 23 + 1 +12 +48 = 84g/mol
Number of mole of NaHCO3 = 0.125 mole
Mass of NaHCO3 =?
Mass = number of mole x molar Mass
Mass of NaHCO3 = 0.125 x 84
Mass of NaHCO3 = 10.5g
Therefore, 10.5g of NaHCO3 is needed.
solution;
Typically plastic volumetric flasks are used when performing trace analysis and analyses may be absorbed OR desorbed from the glass.
An examples is estimating [Na+] in aqueous solutions by a a process like ion-chromatography--if you acid wash your glass volumetric flasks then Na+ in the solution can be absorbed by the glass and then if you base wash your glass volumetric flask, then you may have excess Na+ leaching out into your solution. So to avoid leaching out or absorption of Na+ ions, you would want to use plastic volumetric flasks.
The other instance you would use plastic vessels is measuring out solutions of strong bases like KOH and NaOH--glass slowly dissolves in solutions of bases--you will get potassium or sodium silicate in the end and glass is permanently etched by strong bases--so in these instances you would want to use plastic vessels
As regards acids--the only problem you would have is with HF--glass would be etched/dissolved to form H₂SiF₆ and related soluble compounds
