All questions of Periodic Classification of Elements for Class 10 Exam

The atomic number of an element represents the number of protons in the nucleus of an atom of that element. In the modern periodic table, elements are arranged in order of increasing atomic number. Based on the information given, we can determine the atomic number of the element surrounded by elements with atomic numbers 17, 34, 36, and 53.

Identify the elements:
- The atomic number 17 corresponds to chlorine (Cl).
- The atomic number 34 corresponds to selenium (Se).
- The atomic number 36 corresponds to krypton (Kr).
- The atomic number 53 corresponds to iodine (I).

Determine the missing element:
To find the missing element, we need to look for an element that fits between atomic numbers 34 and 36. The atomic number 35 corresponds to the element bromine (Br). Therefore, bromine is the element surrounded by elements with atomic numbers 17, 34, 36, and 53.

The correct answer is option 'B' (35).

Understanding Eka-Aluminium and Its Oxide Form
Eka-aluminium, known as Gallium (Ga), is a chemical element that belongs to the group of metals in the periodic table. It is important to understand how it reacts and what kind of oxides it forms.
Oxide Formation in Gallium
Gallium typically forms oxides in specific ratios, and the most common oxide it produces is Ga2O3.
Reason for the Answer (E2O3)
- Valency of Gallium:
- Gallium has a valency of +3, which means it can lose three electrons to form compounds.
- Combining with Oxygen:
- Oxygen typically has a valency of -2. To balance the charges, two Gallium atoms (each with a +3 charge) will combine with three oxygen atoms (each with a -2 charge).
- Chemical Formula Derivation:
- The ratio of Gallium to Oxygen in the oxide is thus 2:3, leading to the formula Ga2O3, which corresponds to option E2O3.
Other Options Explained
- EO3: This would imply a different valency not applicable to Gallium.
- E3O2: This would suggest a higher ratio of Gallium, which is not stable.
- EO: Represents a 1:1 ratio, which is also incorrect for Gallium.
Conclusion
Given the chemical properties and valency of Gallium, the oxide it forms is best represented by the formula E2O3, confirming option 'B' as the correct answer.

**Explanation:**

The elements B (Boron), Si (Silicon), and Ge (Germanium) are all located in Group 14 of the periodic table.

**1. Metalloids:**

Metalloids are elements that have properties of both metals and non-metals. They are located along the zigzag line on the periodic table, separating the metals from the non-metals.

**Boron (B):**
- Boron is a metalloid element.
- It is a non-metallic element that is typically brittle in its pure form.
- Boron is a poor conductor of electricity but can act as a semiconductor at high temperatures.
- It has properties of both metals and non-metals, making it a metalloid.

**Silicon (Si):**
- Silicon is a metalloid element.
- It is the second most abundant element in the Earth's crust and is widely used in the technology industry.
- Silicon has a shiny, metallic appearance but is a poor conductor of electricity at room temperature.
- It is used extensively in the production of computer chips and other electronic devices.
- Like boron, silicon has properties of both metals and non-metals, classifying it as a metalloid.

**Germanium (Ge):**
- Germanium is also a metalloid element.
- It has a similar shiny, metallic appearance to silicon.
- Germanium is a semiconductor and has useful electrical properties.
- It is used in transistors, solar cells, and other electronic applications.
- Similar to boron and silicon, germanium exhibits properties of both metals and non-metals, making it a metalloid.

Therefore, the correct answer is option **C) metalloids**, as all three elements B, Si, and Ge are metalloids.