Explanation: Sound waves travel fastest in solids, slower in liquids, and slowest in gases. This is because the speed of sound depends on the elasticity and density of the medium — it travels faster when particles are tightly packed and can transmit vibrations more efficiently. Among the options, iron (a solid) allows sound to travel much faster (around 5130 m/s) than in water (1500 m/s), ice (3200 m/s), or air (331 m/s at 0°C).

Explanation: In computer programming, the term "Beans" is specifically associated with the Java programming language. A JavaBean is a reusable software component written in Java that can be manipulated visually in a builder tool. JavaBeans follow certain conventions such as having a no-argument constructor, providing getter and setter methods, and being serializable. They are widely used in Enterprise Java applications for data encapsulation and to promote modular, reusable code.

Explanation: Boron is a vital micronutrient that assists in the uptake and utilization of calcium and maintains the integrity of cell walls and membranes. It also regulates water movement in plant tissues and plays a role in pollen germination and fruit development. Deficiency of boron can lead to poor calcium translocation, brittle tissues, and reduced water absorption.

Explanation: Kala-azar, also known as visceral leishmaniasis, is caused by the protozoan parasite Leishmania donovani. It is transmitted through the bite of the female Phlebotomus sandfly. The disease primarily affects the liver, spleen, and bone marrow, leading to symptoms such as fever, anemia, weight loss, and darkening of the skin. The term “Kala-azar” literally means “black fever.”

Explanation: The S.I. unit of electric current is the Ampere (A). It is defined as the rate of flow of electric charge through a conductor. One ampere equals one coulomb of charge passing through a point in one second.

Explanation: The Growth Hormone (GH), also known as Somatotropin, is secreted by the anterior lobe of the pituitary gland, which is located at the base of the brain. This hormone stimulates growth, cell reproduction, and regeneration in humans and other animals. It plays a vital role in increasing height during childhood and adolescence, regulating metabolism, and maintaining muscle and bone mass. A deficiency of GH causes dwarfism in children, while excess secretion leads to gigantism or acromegaly.

Explanation: The Sinoatrial (SA) node is a specialized group of modified cardiac muscle fibers located in the right atrium of the heart, near the opening of the superior vena cava. It generates electrical impulses (action potentials) that initiate each heartbeat. Therefore, it is known as the natural pacemaker of the heart.

The impulses from the SA node spread across the atria, causing them to contract, and are then transmitted to the Atrioventricular (AV) node, Bundle of His, and Purkinje fibers to coordinate ventricular contraction.

Normal rate of SA node firing: ~70–75 impulses per minute (in a healthy adult at rest).

In case of SA node failure: Artificial pacemakers are implanted to maintain normal rhythm.

Explanation: 1 Gigabyte (GB) is equal to 1024 Megabytes (MB). Computer memory and storage are measured in powers of 2 (binary system), where 1 KB = 1024 bytes, 1 MB = 1024 KB, and 1 GB = 1024 MB.