Olympiad Test Level 2: Technological Developments and Inventions- 1 - Class 7 MCQ

Name of the Indian Origin Scientist who developed the world's first wireless pacemaker: Dr. Vivek Reddy
Explanation:
- Dr. Vivek Reddy is an Indian origin scientist who has developed the world's first wireless pacemaker.
- He is a renowned cardiologist and electrophysiologist.
- Dr. Reddy is currently serving as the Director of Cardiac Arrhythmia Services at Mount Sinai Hospital in New York.
- The wireless pacemaker developed by Dr. Reddy is a breakthrough in the field of cardiology as it eliminates the need for wired connections to the heart.
- This wireless pacemaker offers several advantages over traditional pacemakers, including reducing the risk of infection, providing greater patient comfort, and allowing for easier upgrades or replacements.
- Dr. Reddy's groundbreaking work in developing the wireless pacemaker has revolutionized the field of cardiac rhythm management.
- His contributions have been recognized globally, and he has received numerous awards and honors for his exceptional research and inventions.
- Dr. Vivek Reddy continues to make significant contributions to the field of cardiology, improving patient outcomes and advancing medical technology.

World's lightest material developed by ISRO scientists is: Silica Aerogel
Explanation:
Silica Aerogel is the name of the world's lightest material developed by ISRO scientists. Here is a detailed explanation about Silica Aerogel:
- What is Silica Aerogel?
- Silica Aerogel is a synthetic porous material derived from silicon dioxide (SiO2).
- It is also known as "frozen smoke" or "solid smoke" due to its translucent appearance.
- It is extremely lightweight and has a low density, making it one of the lightest materials known to date.
- Properties of Silica Aerogel:
- Ultra-Low Density: Silica Aerogel has a density ranging from 0.0011 to 0.03 g/cm³, which makes it lighter than air.
- Excellent Insulator: It has exceptional thermal insulation properties, with a thermal conductivity of around 0.03 W/mK.
- High Porosity: Silica Aerogel is composed of a highly porous structure, with up to 99.8% of its volume being empty space.
- Translucent Appearance: It appears translucent or semi-transparent, allowing light to pass through.
- Applications of Silica Aerogel:
- Insulation: Silica Aerogel is widely used as an insulating material in various industries, including aerospace, construction, and electronics.
- Energy Efficiency: It helps in reducing heat loss, making it valuable for energy-efficient applications.
- Thermal Protection: Silica Aerogel is used in thermal protection systems for spacecraft and spacesuits, providing insulation from extreme temperatures.
- Environmental Remediation: It can be used for oil spill cleanup, as it has a high absorption capacity for hydrocarbons.
- Soundproofing: Silica Aerogel can also be used as a soundproofing material due to its low density and high porosity.
In conclusion, Silica Aerogel developed by ISRO scientists is the world's lightest material known for its ultra-low density, excellent insulation properties, and various applications in different industries.

Reasons why many transplanted seedlings do not grow:
- Loss of root hairs: During transplantation, the delicate root system of the seedling may suffer damage, leading to the loss of root hairs. Root hairs play a crucial role in absorbing water and nutrients from the soil. Without a sufficient number of intact root hairs, the seedling may struggle to establish itself and obtain the necessary resources for growth.
- Poor soil conditions: The new soil in which the seedling is transplanted may lack essential minerals and nutrients required for healthy growth. If the soil does not provide the necessary resources, the seedling may not be able to thrive and may eventually wither.
- Roots not adapting to new soil: When a seedling is transplanted, its roots need to adapt to the new soil conditions. If the new soil differs significantly from the soil in which the seedling initially grew, the roots may have difficulty adjusting and establishing a strong hold. This can lead to poor nutrient uptake and hinder the growth of the seedling.
- Damage to leaves: Transplantation can sometimes result in physical damage to the leaves of the seedling. Leaves are essential for photosynthesis, the process by which plants convert sunlight into energy. If the leaves are damaged or compromised, the seedling may struggle to produce enough energy to support growth.
Overall, the loss of root hairs, poor soil conditions, roots not adapting to new soil, and damage to leaves are all potential reasons why many transplanted seedlings do not grow successfully.

Joseph Lister  introduced carbolic acid to sterilise surgical instruments and to clean wounds, which led to a reduction in postoperative infections and made surgery safer for patients.

The device used to listen to the vibrations of the heart and lungs is called a stethoscope.



Explanation:


A stethoscope is a medical instrument that is commonly used by healthcare professionals to listen to the internal sounds of the body, particularly the heart and lungs. It consists of two earpieces connected to flexible tubing, which is then attached to a chest piece. The chest piece has a diaphragm and a bell, which are placed on the patient's body to detect and amplify the sounds.
Key Points:
- A stethoscope is used to listen to the vibrations produced by the heart and lungs.
- It is a common tool used by healthcare professionals.
- The stethoscope consists of earpieces, tubing, and a chest piece.
- The chest piece has a diaphragm and a bell to detect and amplify sounds.
- It allows healthcare professionals to listen to the internal sounds of the body and detect any abnormalities or irregularities in the heartbeat or breath sounds.

The system for writing for blind was invented by Louis Braille

Michael Faraday discovered link between electricity and magnetism called electromagnetism.

Explanation:

The given metal is soft and can be easily cut with a knife. It catches fire when exposed to air and water and is also used in street lights.

Identifying the metal:

To identify the metal, let's analyze the given characteristics:

• The metal is soft and can be easily cut with a knife. This eliminates metals like iron, steel, and copper, which are harder and cannot be easily cut with a knife.


• The metal catches fire when exposed to air and water. This indicates that it is a highly reactive metal.


• The metal is used in street lights. This suggests that it is a metal that can be used in electrical applications.

Determining the correct answer:

Considering the above characteristics, the metal 'X' can be identified as Sodium (Na).

• Sodium is a soft metal that can be easily cut with a knife.


• It is highly reactive and catches fire when exposed to air and water.


• Sodium is also used in street lights, where it is combined with other elements to produce a bright yellow light.

Therefore, the correct answer is A: Sodium.

The incorrect pair among the given inventions and inventors is:
(iv) Cinema - Bartolomeo Cristofori
Explanation:
- (i) Atomic bomb - J. Robert Oppenheimer: J. Robert Oppenheimer is credited with leading the team of scientists that developed the atomic bomb during the Manhattan Project in the 1940s. This invention had a significant impact on warfare and the world.
- (ii) Piano - Georges Audemars: This is a correct pair. Georges Audemars is not associated with the invention of the piano. The piano was invented by Bartolomeo Cristofori, an Italian musical instrument maker, in the early 18th century.
- (iii) Steel - Henry Bessemer: This is a correct pair. Henry Bessemer is credited with the invention of the Bessemer process, which revolutionized the production of steel in the mid-19th century. His invention made steel production faster, cheaper, and more efficient.
- (iv) Cinema - Bartolomeo Cristofori: This is the incorrect pair. Bartolomeo Cristofori is known for inventing the piano, not cinema. Cinema, or motion pictures, is attributed to various inventors and pioneers such as Thomas Edison, the Lumière brothers, and Eadweard Muybridge.
Therefore, the correct answer is option D: (ii) and (iv).

He was Ronald Ross