Write one use of urea.
One use of urea is as a fertilizer.
Question ID: 261
Uploaded on: September 22, 2024
Write the structural formula of propanone. OR Wohler first prepared an organic compound from an inorganic compound in the laboratory. What is the organic compound?
Structural formula of propanone
OR
Wöhler first prepared the organic compound urea from the inorganic compound ammonium cyanate in the laboratory.
Question ID: 262
Uploaded on: September 22, 2024
Give an example of a biodegradable natural polymer.
An example of a biodegradable natural polymer is starch.
Question ID: 263
Uploaded on: September 22, 2024
Write with reason in which layer among the layers of the atmosphere the pressure is the highest.
The troposphere is the layer of the atmosphere where the pressure is the highest. This is because the troposphere contains the majority of the atmosphere's mass, including water vapor, gases, and particulate matter.
Question ID: 264
Uploaded on: September 22, 2024
Find out the ratio of the volumes occupied by 32 g O2 and 44 g CO2 gases at 27oC temperature and 700 mm Hg pressure. (C = 12, O = 16). OR A fixed mass of a gas occupies a volume of 520 cm3 at -13oC temperature. Keeping the pressure unchanged, when the gas is heated the volume of the gas increases to 700 cm3. What is the final temperature of the gas in degree Celsius?
Molar Mass of O2 = 32
Molar Mass of CO2 = 44
Moles of O2 = 32\over 32 = 1
Moles of CO2 = 44\over 44 = 1
Ideal gases Equation: PV = nRT
or, V ∝ nRT\over P
At constant temperature and pressure, the volume is directly proportional to the number of moles of gas:
V_1\over V_2 =n_1\over n_2
or, V_1\over V_2 =1\over 1
Since both gases have the same number of moles under the same conditions of temperature and pressure, the ratio of their volumes is 1:1.
OR
V1 = 520 cm3
V2 = 700 cm3
T1= −13ºC = 273 - 13 = 260 K
Charles' Law: V_1\over T_1 = V_2\over T_2
T2 = V_2\over T_2 × 260 = 350 K
or, T2 = 350 K - 273 = 77°C
The final temperature is 77°C.
Question ID: 265
Uploaded on: September 22, 2024
Mention two features of the image formed by a simple camera. OR Where in front of a concave mirror image of an extended object placed at infinity will be formed by the mirror? Mention one feature of the image.
Two Features of the Image Formed by a Simple Camera:
OR
The image of an extended object placed at infinity will be formed at the focal point of the concave mirror.
Feature of the Image: The image will be point-sized (highly diminished) and inverted.
Question ID: 266
Uploaded on: September 22, 2024
Mention one similarity and one dissimilarity between electromotive force and potential difference.
Similarity:
Both emf and potential difference measure electrical energy per unit charge.
Dissimilarity:
Emf is the voltage generated by a source with no current, while the potential difference is the voltage between two points when current flows.
Question ID: 267
Uploaded on: September 22, 2024
By giving an example of an ionic compound shows that its ions do not obey the octet rule. OR Explain why the melting point of sodium chloride is much greater than that of glucose.
An example of an ionic compound that does not obey the octet rule is lithium oxide (Li2O).
Lithium (Li) has 3 electrons and loses 1 electron to form Li+, achieving a stable configuration with only 2 electrons, not 8 (octet).
Oxygen (O) gains 2 electrons to form O2-, which follows the octet rule.
OR
Sodium chloride (NaCl) has a much higher melting point than glucose because NaCl has strong ionic bonds that require more energy to break. Whereas, glucose has weaker covalent bonds and intermolecular forces, leading to a lower melting point.
Question ID: 268
Uploaded on: September 22, 2024
Shows that F forms an ionic bond with Na but it forms a covalent bond with H. [2] (The atomic numbers of H, F and Na are 1, 9, and 11 respectively)
Ionic Bond Between Na and F:
When Na and F react: Na+F→Na + +F - (Ionic Bond)
Covalent Bond Between H and F:
When H and F react: H + F → HF (Covalent Bond)
Question ID: 269
Uploaded on: September 22, 2024
Write, with the balanced chemical equation, what happens when nitrogen gas is passed over calcium carbide heated at 1100ºC.
When nitrogen gas is passed over heated calcium carbide (CaC₂) at 1100°C, calcium cyanamide (CaCN2) and carbon (C) are formed.
Balanced Chemical Equation:
CaC2 + N2 {\overset \text {1100\ °C}{\longrightarrow}} CaCN2 + C
This reaction is used in the production of calcium cyanamide, which is an important fertilizer.
Question ID: 270
Uploaded on: September 22, 2024
Write the balanced chemical equation of the reaction for the formation of metallic iron from ferric oxide by thermit process. Write an application of the process. OR Write the balanced chemical equation of the reaction of the reaction that occurs when a piece of metallic iron is added to an aqueous solution of CuSO4. What information is obtained from this reaction about the relative position of Cu and Fe in the activity series of metals?
Balanced Chemical Equation for the Thermit Process:
Fe2O3 + 2Al → 2Fe + Al2O3
In this reaction, ferric oxide (Fe2O3) reacts with aluminium (Al) to produce metallic iron (Fe) and aluminium oxide (Al2O3).
The thermit process is commonly used for welding railway tracks and repairing metal structures due to the high temperature produced during the reaction.
OR
Balanced Chemical Equation:
Fe + CuSO4 → FeSO4 + Cu
Information from the Reaction:
This reaction shows that iron (Fe) is more reactive than copper (Cu) because iron displaces copper from its compound. Hence, Fe is placed above Cu in the activity series of metals.
Question ID: 271
Uploaded on: September 22, 2024
Select the members of a homologous series from the following compound and arrange them in increasing order or their molecular weights : CH3COOH, CH3CH2OH, CH3OCH3, CH3OH, C2H4, C2H6, CH3CH2CH2OH, C3H4. OR Write with an example of what is meant by functional group.
Members of a Homologous Series (Alcohols):
The alcohols from the given compounds are:
OR
A functional group is a specific group of atoms within a molecule that is responsible for the characteristic chemical reactions of that molecule. Functional groups determine the properties and reactivity of organic compounds.
Example:
In ethanol (C2H5OH), the functional group is the hydroxyl group (-OH).
Question ID: 272
Uploaded on: September 22, 2024