Answer: C) +4 Explanation: The given compound is NaHCO3 Sodium bicarbonate which is commonly known as Baking soda. Oxidation numbers are the charges on ions. When a neutral atom loses electrons it becomes positively charged. When a neutral atom gains electrons it becomes negatively charged.   Here the C represents the oxidation state of carbon in this compound. Compounds are electrically neutral, which is why we set the sum of the oxidation states equal to zero. Sodium has a +1 oxidation state. Hydrogen has a +1 oxidation state. Oxygen has a -2 oxidation state. There are three oxygen atoms, which means the total oxidation state provided by both oxygen ions is -6. Adding up these oxidation states we get: 1 + 1 + (-6) + C = 0 -4 + C = 0 => C = 4 This means the oxidation state of carbon in this compound is +4.

Answer: D) All the above Explanation: Common properties of Minerals are :   1. All minerals are formed in a natural process. 2. Minerals are inorganic 3. Minerals are crystalline solids. 4. Every mineral is an element or compound with a definite chemical composition.

Answer: D) 5 Explanation: By trial and error method, we get2880/3 = 960 is not a perfect square2880/4 = 720 is not a perfect square2880/5 = 576 which is perfect square of 24Hence, 5 is the least number by which 2880 must be divided in order to make it into a perfect square.

Photoautotrophs are those organisms that can make their own food using sun light with the help of the process of photosynthesis. Plants can prepare their own food using sunlight. Hence they are Photoautotrophs.

Answer: B) Urochrome Explanation: The yellow color of urine is due to the presence of a yellow pigment, urochrome. The color of normal urine is usually light yellow to amber. Generally the greater the solute volume the deeper the color.

Answer: C) Glass Explanation: Sound is a mechanical vibration and needs a medium for propagation. The higher the density of the medium, the faster the sound travels. So, sound cannot travel through vacuum.   As the sound travels faster in solids than liquids and gases, sound travels faster in the glass than Air and water.

Answer: C) decrease by 4% Explanation: Here, x = 20 and y = - 20Therefore, the net % change in value=x + y + xy100 %= 20 + -20 + 20 × -20100%  or  - 4% Since the sign is negative, there is a decrease in value by 4%.

Answer: A) 14.28 % profit Explanation: Let 1kg of Rs. 100 then 840gm is of Rs. 84.Now (label on can 1kg but contains 840kg ) so for customer it is of Rs. 100 and further gives 4% discount [he sells his article on 4% loss on cost price.] So now S.P = Rs. 96But actually it contains 840 gm so C.P for shopkeeper = Rs. 84S.P = Rs. 96C.P = Rs. 84Profit% = {(S.P-C.P)/C.P}x100{(96-84)/84} x 100 = 14.28571429% PROFIT.