Which of the following options represents the product(s) of the reaction given below?
MnO2 + 4HCl →
Only MnCl2
MnCl2, Cl2 and 2H2O
Only H2O
Only Cl2
The given reaction is between manganese dioxide (MnO\(_2\)) and hydrochloric acid (HCl). This is a classic example of a redox reaction where MnO\(_2\) acts as an oxidizing agent and HCl acts as a reducing agent. To determine the products, we need to balance the chemical equation, considering the oxidation states of the elements involved.
Identify Reactants: The reactants are Manganese dioxide (MnO\(_2\)) and Hydrochloric acid (HCl).
Determine Oxidation States:
Predict Products (Redox Reaction):
Write the Unbalanced Equation:
\[ \text{MnO}_2 + \text{HCl} \rightarrow \text{MnCl}_2 + \text{Cl}_2 + \text{H}_2\text{O} \]
Balance the Equation:
Final Balanced Equation:
\[ \text{MnO}_2 + 4\text{HCl} \rightarrow \text{MnCl}_2 + \text{Cl}_2 + 2\text{H}_2\text{O} \]
The products are manganese(II) chloride (MnCl\(_2\)), chlorine gas (Cl\(_2\)), and water (H\(_2\)O).
Correct Option: B) MnCl\(_2\), Cl\(_2\) and 2H\(_2\)O
Which of the following compounds is obtained when gypsum is heated at 373 K?
CaO
CaSO4.(\( \frac{1}{2} \) H2O)
CaSO4.2H2O
CaSO4.5H2O
The question asks to identify the compound formed when gypsum is heated at a specific temperature (373 K). This involves understanding the thermal decomposition of gypsum.
Correct Option: B) \[\text{CaSO}_4 \cdot (\frac{1}{2} \text{H}_2\text{O})\] is calcium sulfate hemihydrate, which is Plaster of Paris. This is the compound formed when gypsum is heated at 373 K.
The question asks to identify the molecule that serves as the primary information source for protein synthesis. This relates to the central dogma of molecular biology, which describes the flow of genetic information in biological systems.
Correct Option: A) Deoxyribonucleic acid (DNA) is the primary genetic material in most organisms. It contains the hereditary information that dictates the synthesis of all proteins in a cell. The sequence of nucleotides in DNA directly codes for the sequence of amino acids in proteins, through an RNA intermediate.
This problem involves arranging six people around a circular table based on given positional clues. We need to deduce the final arrangement and then determine the position of E with respect to C.
Correct Option: D) Second to the left
The question asks about the essential element required for the synthesis of thyroxin hormones. This is a direct knowledge-based question related to human physiology and nutrition.
Correct Option: C) Iodine is absolutely essential for the synthesis of thyroxin hormones. The thyroid gland actively takes up iodine from the bloodstream to produce these hormones.
To find the molecular mass of a compound, we need to sum the atomic masses of all the atoms present in its chemical formula. For HNO₃, we will identify the elements, their respective atomic masses, and the number of atoms of each element, then calculate the total.
Correct Option: A) 63 u
All 36 students in a class are standing in a row facing north. Preeti is 12th from the right end while Alisha is 22nd from the left end. How many people stand between Preeti and Alisha?
To find the number of people between Preeti and Alisha, we need to determine their positions from a common reference point (either the left or right end). We will calculate Preeti's position from the left end and then find the number of students between her and Alisha.
Total number of students: \[ \text{Total students} = 36 \]
Preeti's position from the right end: \[ \text{Preeti's position from right} = 12^{\text{th}} \]
Calculate Preeti's position from the left end: The formula to convert position from one end to the other is: \[ \text{Position from left} = (\text{Total students} - \text{Position from right}) + 1 \] \[ \text{Preeti's position from left} = (36 - 12) + 1 = 24 + 1 = 25^{\text{th}} \] So, Preeti is \(25^{\text{th}}\) from the left end.
Alisha's position from the left end: \[ \text{Alisha's position from left} = 22^{\text{nd}} \]
Determine the number of students between Preeti and Alisha: Since both positions are from the left end, we can directly find the number of students between them. Preeti is at \(25^{\text{th}}\) position from the left, and Alisha is at \(22^{\text{nd}}\) position from the left. This means Alisha is to the left of Preeti. The students between them are those at positions \(23^{\text{rd}}\) and \(24^{\text{th}}\) from the left. \[ \text{Number of students between} = \text{Preeti's position from left} - \text{Alisha's position from left} - 1 \] \[ \text{Number of students between} = 25 - 22 - 1 = 3 - 1 = 2 \]
There are 2 students standing between Preeti and Alisha.
D) 2
To solve this problem, we need to apply the given rules to each letter in the word PASTRY. We will identify each letter as either a consonant or a vowel. For consonants, we will change them to the letter immediately preceding them in the English alphabet. For vowels, we will change them to the letter immediately succeeding them. Finally, we will count the number of vowels in the newly formed group of letters.
Correct Option: B) One
If the refractive index of air, water and crown glass are n1, n2 and n3, respectively, then ______.
n1 < n2 = n3
n1 > n2 > n3
n1 = n2 < n3
n1 < n2 < n3
To determine the correct relationship between the refractive indices of air, water, and crown glass, we need to recall the typical values or relative magnitudes of refractive indices for these common optical media. The refractive index is a measure of how much the speed of light is reduced when passing through a medium, and it also indicates the optical density of the medium.
Correct Option: D) \(n_1 < n_2 < n_3\)