Why Is The Color Of Urine Sometimes White And Sometimes Yellowish?

When your urine(pee) yellow it means your dehydrated.(means you don't drink enough water)if its clear/white it means you have enough water in your body to give clear/white urine out.

Urine is not actually colourless; there exist urochrome, uroerythrin, and urobilin pigments to colour the urine. Presence of drugs, etc. may also contribute towards coloration of the urine. The ideal colour of the urine should be light yellowish to amber. Any other colour indicates some disorders. Because of some deficiency or disorders, urine may become red, pink, orange, black, green, blue, gray, brown, or Coke coloured.

As already mentioned, the typical shade of the normal urine is pale or light yellow (just not to double up with colourless water!). Different shades of yellow are due to the availability of the different particles present in the urine. With the extra availability of the vitamin B2 or riboflavin than the body needs, the urine may become bright yellowish (can be used as an indicator that the body is not deficient of vitamin B2). Concentrated or dehydrated urine also caused to be of deep yellow in colour.

The white coloured urine or in the medical terminology, the colourless urine is caused due to heavy consumption of fluid recently. After consuming a plenty of water, urine generally become white in colour, thereby temporarily hides the original colour (heavy intake of water to produce colourless urine cannot be considered as cure against the colourful prescription of your doctor). This also tells that the urine is dilute enough causing less availability of the coloured pigments and thereby giving the colourless colour of the urine.

The color of urines depends on many factors. The more you take water the more whitish the urine appears. If you are dehydrated the urine color changes to dark orange.
The color of urine also depends upon the food you eat or the medications you take.Urine consists of excess water and waste products that have been filtered from the blood by the kidneys. Its natural yellow color appears due to excretion of urochrome, a pigment from blood.
Mostly if you are a healthy person the change in urine color is temporary. However if the change in urine color is continuously seen, this may indicate a serious disease. In this case a doctor must be consulted.
BLUE/GREEN URINE results due to blue dye such as methylene blue, a component present in several medications.
BROWN/BLACK URINE may results due to L-dopa or melanin excretion as well as copper or phenol poisoning. Medicine such as chloraquine and primaquine, furazolidone, metronidazole, nitrofurantoin, cascara/senna laxatives, methocarbamol, and sorbitol also produce the same results.
ORANGE PINK URINE can result from abundant uric acid crystals which can be seen in acidic urine of patients who have undergone intestinal by-pass surgery or are receiving chemotherapy for malignancy.
RED/PINK urine implies the presence of red cells, free hemoglobin etc. in this case doctor must be consulted immediately.
Hope this answers your questions.

Milky white urine  or chalk is mixed in urine

Diabetic patients have colourless urine generally due to the excessive thirst that they experience

There is no such thing as "white" urine. Unless you meant to say that your urine is clear.  As far as it being yellow that might be a sign of dehydration and/or you've been taking Vitamin B supplements.

Hey guyz, I pass motion. And after that I pee white pee a lot say, 2-3minutes. After that I tyring passing motion again. I checked and there is still poo. But I can't get it out. Why?

White pee is chyluria caused by filaria, specifically bancrofti.  Doctors in america stopped treating people for it in the mid 1920's.  They try to deny it exist in america.  Filaria is the main cause of most forms of cancer.
ASK YOUR DOCTOR FOR A LYMPHOGRAM!

Yellow color of urine is normal urine, It is because of urobolin and urobilinogen. Or it may be because of some drugs.

And, white color of urine is because of Chyle particles present in urine in case of Filariasis, sometime due to contamination of semen, and sometime due to excess of amorphous phosphate.