ANS:B - Foot

Explanation: All except Foot are parts of hand.

ANS:C - 4

The outermost orbit of an atom is called as valence shell. The number of valence electrons present in a valence shell is based on its capacity. For example: take silicon a semiconductor, which has 4 valance electrons.

ANS:E - all the above.

Before discharging foul sewage into rivers or other water bodies, it is essential to treat it to remove pollutants and pathogens, protecting the environment and public health. Treatment processes aim to reduce the organic and inorganic content, remove solids, and disinfect the wastewater. Let's discuss each of the treatment methods mentioned:

1. Screening: Screening is often the first step in wastewater treatment. It involves the removal of large debris and solids from the sewage using screens or grates. This process prevents large objects such as sticks, stones, plastics, and other debris from entering the treatment system, which could cause damage to pumps, pipes, and other equipment downstream. Screening helps to protect pumps, prevent blockages, and improve the efficiency of subsequent treatment processes.
2. Sedimentation: Sedimentation, also known as settling, is a physical process in which suspended solids and particles in wastewater settle out under the influence of gravity. This can occur in sedimentation tanks or clarifiers, where the flow velocity of the wastewater is reduced, allowing particles to settle to the bottom. Sedimentation removes settleable solids, such as sand, grit, and organic matter, from the wastewater, producing a clearer effluent that is easier to treat in subsequent processes.
3. Oxidation: Oxidation processes, such as biological oxidation or chemical oxidation, are used to break down organic pollutants in wastewater. Biological oxidation involves the use of microorganisms to consume organic matter and convert it into simpler, less harmful substances through aerobic (with oxygen) or anaerobic (without oxygen) processes. Chemical oxidation involves the addition of oxidizing agents, such as chlorine or ozone, to chemically react with and degrade organic compounds. Oxidation processes help to reduce the biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of the wastewater, improving its quality before discharge.
4. Sludge Digestion and Disinfection: After primary treatment processes, sewage often undergoes secondary treatment, which may include processes such as sludge digestion and disinfection. Sludge digestion involves the biological decomposition of organic solids present in wastewater sludge by anaerobic bacteria, producing methane gas and stabilized sludge. Disinfection is the final step in wastewater treatment, where pathogens such as bacteria, viruses, and protozoa are destroyed or inactivated to ensure that the treated effluent meets regulatory standards for discharge. Common disinfection methods include chlorination, ultraviolet (UV) irradiation, and ozonation.

• All of the above.

ANS:B - full subtractor

ANS:B - path functions

𝑑𝑊dW and 𝑑𝑞dq are not exact differentials because 𝑞q and 𝑊W are path functions. In thermodynamics, state functions are properties whose values depend only on the current state of a system and not on how that state was reached. Examples of state functions include internal energy 𝑈U, enthalpy 𝐻H, entropy 𝑆S, and Gibbs free energy 𝐺G. State functions are exact differentials, meaning their differentials (𝑑𝑈dU, 𝑑𝐻dH, 𝑑𝑆dS, 𝑑𝐺dG) are exact and do not depend on the path taken to reach a particular state. In contrast, path functions (also known as inexact differentials) depend on the path followed during a process to determine their values. Heat (𝑞q) and work (𝑊W) are examples of path functions. The heat transferred to or from a system and the work done on or by a system depend not only on the initial and final states but also on the specific path taken between those states. As a result, 𝑑𝑞dq and 𝑑𝑊dW are not exact differentials. Therefore, the correct answer is path functions.

ANS:C - Air Marshal Makarand Ranade

Air Marshal Makarand Ranade took over as Director General (Inspection and Safety) at Air HQ New Delhi on December 1, 2023, succeeding Air Marshal Sanjeev Kapoor, who retired after more than 38 years of distinguished service.

ANS:B - China

China has successfully tested its first fully solar-powered unmanned aerial vehicle (UAV).