Samples of water have been sourced from a river, a tap and a rainwater harvesting tank. However, upon testing, all the samples contain hydrogen and oxygen in the ratio of 1 : 8 by mass irrespective of the source of water. Which of the following laws does this prove?

Which of the following statements is/are correct?

(a). Law of conservation of mass states that mass can neither be created nor destroyed in a chemical reaction. (b). The law of definite proportions states that in a chemical substance the elements are always present in definite proportions by mass. (c). Dalton's atomic theory states that matter consists of indivisible particles called atoms and that atoms of a given element are all identical and can neither be created nor destroyed.

The combining capacity of an element is called its

Which of the following statements are incorrect?

(a). An ion is a charged particle. (b). Ionic compunds are formed from a combination of metals with non-metals. (c). A negatively charged ion is called an anion.

Which of the following molecules is/are triatomic?

(a). NH₃ (b). H₂O (c). CO₂

The atomic mass of zinc is 65.37 u. Which of the following is the correct weight of 1 atom of zinc?

Match the following symbols with the names of corresponding elements:

What is the correct number of hydrogen atoms in 0.25 moles of water?

Which of the following statements is/are incorrect?

(a). Atoms of most elements are able to exist independently. (b). Atoms form molecules and ions. (c). An atom is a group of molecules tightly held together by attractive forces.

What is the mass of one molecule of water?

What is the number of grams of Cr in 85 grams of Cr₂S₃?

Directions: In the question given below, there are two statements labelled as Assertion (A) and Reason (R). Mark your answer as per the codes provided below:

A. Both A and R are true and R is the correct explanation of A. B. Both A and R are true but R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true. E. Both A and R are false.

Assertion (A): Graphite and diamond though made from carbon, show different properties. Reason (R): This supports Dalton's atomic theory of matter.

Directions: In the questions given below, there are two statements labelled as Assertion (A) and Reason (R). Mark your answer as per the codes provided below:

A. Both A and R are true and R is the correct explanation of A. B. Both A and R are true but R is not the correct explanation of A. C. A is true but R is false. D. A is false but R is true. E. Both A and R are false.

Assertion: In water, 1 gram of hydrogen combines with 16 grams of oxygen. In hydrogen peroxide, 1 gram of hydrogen combines with 8 grams of peroxide.

Reason: The ratio of oxygen in water and hydrogen peroxide combining with the same amount of hydrogen is the law of multiple proportions.

Which of the following statements is/are correct?

(a). Naturally occurring oxygen is a mixture of atoms of slightly different masses called isotopes. (b). Formula mass and not molecular mass is used for a substance whose constituent particles are ions. (c). Basic radicals carry negative charge.

Which of the following statements is/are correct?

(a). The word “mole” was introduced in 1896 by Wilhelm Ostwald. (b). The mass of 1 mole of a substance is equal to its relative atomic or molecular mass in grams. (c). The quantity of a substance can be characterised by the valency of its molecules.

Which of the following is paired incorrectly with its chemical name and chemical formula?

Match the columns.

Which of the following compounds is/are made up of charged ions?

(a). CaO (b). NaCl (c). MgCl₂