General Chemistry

The correct answer to the question about which cell is used in automobiles and inverters is the Lead storage cell. Let us understand why this is the suitable choice by considering the options provided:

1. Mercury cell: Mercury cells are primary cells typically used in small electronic devices like watches and hearing aids. They provide a stable voltage but are not suitable for high current applications required in automobiles and inverters.
2. Dry cell: Dry cells are commonly used in household batteries for flashlights and portable radios. While versatile, they do not provide the high capacity necessary for automotive or backup power applications.
3. Lead storage cell: These are commonly known as lead-acid batteries. They are rechargeable and provide a high current, making them ideal for automotive and inverter applications. Their ability to supply large amounts of power makes them the standard choice for starting, lighting, and ignition (SLI) in vehicles.
4. Fuel cell: Fuel cells convert chemical energy directly into electrical energy through electrochemical reactions, typically hydrogen and oxygen. While promising for vehicles, they are not the typical choice for current mainstream automobiles and backup inverters.

Thus, the Lead storage cell is the correct choice because its characteristics perfectly suit the requirements for use in automobiles and inverters.

The question asks for the reason behind the low concentration of oxygen in the blood and tissues of people living at high altitudes. Let's break down the answer step-by-step:

1. Understanding Altitude and Atmospheric Pressure: At higher altitudes, the atmospheric pressure is significantly lower than at sea level. Atmospheric pressure decreases with altitude due to the thinning of the atmosphere. This leads to fewer air molecules, including oxygen molecules, being present in a given volume of air.

2. Effect on Oxygen Concentration: The partial pressure of oxygen also decreases with altitude, meaning that there is less oxygen available to be absorbed into the bloodstream with each breath. Despite the percentage of oxygen remaining roughly the same (around 21%), the reduced atmospheric pressure means there is less total oxygen available.

3. Physiological Impact: With lower oxygen availability, the body and its tissues receive less oxygen, leading to low oxygen concentration in the blood. This condition can result in symptoms such as breathlessness, fatigue, and at times, altitude sickness.

Therefore, the correct explanation for the low concentration of oxygen in the blood and tissues of people living at high altitudes is due to low atmospheric pressure.

Correct Answer: Low atmospheric pressure

To determine the correct statements regarding the properties of a Mercury cell, let's analyze each given option:

1. Statement (A): "It converts energy of combustion into electrical energy"
   A Mercury cell converts chemical energy into electrical energy, not energy from combustion. Therefore, this statement is incorrect.
2. Statement (B): "It is rechargeable"
   Mercury cells are typically primary cells, meaning they are not rechargeable. Therefore, this statement is incorrect.
3. Statement (C): "The cell reaction involved is Zn(Hg) + HgO(s) → ZnO(s) + Hg(l)"
   This statement accurately describes the cell reaction in a Mercury cell, where zinc amalgam (Zn(Hg)) reacts with mercuric oxide (HgO) to produce zinc oxide (ZnO) and liquid mercury (Hg). Therefore, this statement is correct.
4. Statement (D): "It is a low current device used in hearing aids"
   Mercury cells are known for providing a stable voltage and are used in low-current devices such as hearing aids and watches. Therefore, this statement is correct.

After evaluating all the statements, we find that the correct description of properties for a Mercury cell corresponds to statements (C) and (D). Thus, the correct answer is:

To identify the correct unit for , we must understand what represents. In electrochemistry, is known as the cell potential or electromotive force (emf) of an electrochemical cell. It represents the potential difference that drives electrons from the anode to the cathode in a cell.

The standard unit of electric potential or electromotive force is the volt (V).

Let's analyze the options provided and justify why the correct answer is V:

• V m^-1: This is the unit for electric field strength, not potential difference. Thus, it is not suitable for .
• S cm^-1: This unit stands for conductivity, which is unrelated to the cell potential.
• V: This is the standard SI unit for potential difference or electromotive force, making it the correct unit for .
• S cm^-2 mol^-1: This is not a standard unit for any fundamental electrochemical or electrical property of a cell. It could represent a complex quantity, but it does not apply to cell potential.

Thus, the unit of is V.