Https://edu.rsc.org/resources/the-rate-of-reaction-of-magnesium-with-hydrochloric-acid/1916.article
Answer: The correct answer is Heterogeneous mixture
Explanation:
Heterogeneous mixture are those mixture in which:
- Substance is distributed in non uniform manner.
- Two distinct layers are formed
Thus when water and dirt are mixed together it results in the formation of a heterogeneous mixture and after sometimes two different layers will be observed.
Hence, in the bottle there is a heterogeneous mixture of water and dirt.
Answer: The black ball will have more mass than the white ball.
Explanation: Density of a substance is defined as the ratio of mass and volume occupied by the substance.
Mathematically,

We are given that the two balls are of same size, which means that the volume of both the balls are same. We are also given that the black ball is more dense than the white ball, which means that the black ball will have more mass.
As, 
PH (potential of hydrogen) is a numeric scale that is used to show the acidity or basicity of an aqueous solution. It tells how acidic or alkaline a substance is . The pH values ranges from 0 to 14, such that acidic solutions have values between 1 to 6.9 with most acidic having a pH value of 1 and those that are basic have values from 7.1 to 14, with most acidic having a value of 14. Acidic compounds contain replaceable hydrogen ions while basic compounds contain hrdroxyl ions. In this case, a coke has a pH of 3.5 (acidic) which means that it has an excess of hydrogen ions (H+) and would be called an acid.
Answer:
divide the # of molecules by avogadros number and get 3.48 x 10^-6
Explanation: