Answer:
He developed the concept of concentric electron energy levels
Explanation:
Before Bohr's model, Rutherford's model was proposed. This model explains most of the properties of the atom but failed to explain the stability of the atom.
As per Rutherford's model, electrons revolve around the nucleus in the orbit.
But revolving electron in their orbit around nucleus would give up energy and so gradually move towards the nucleus and therefore, eventually collapse.
Bohr's proposed that the electrons around the nucleus move orbit of fixed energy called "stationary states". Electrons in these stationary states do not radiate energy.
Therefore, proposal of concentric electron energy levels refine the atomic models.
The correct option is STRONTIUM.
Strontium is a group 2 element, that means it has two electrons in its outermost shell. This element will prefer to lose these two electrons in its outermost shell in order to attain the octet form, therefore, it will form electrovalent bond with non metals which it can donate two electrons to.
Answer:
Option (D)
Explanation:
Weathering is usually defined as the disintegration of rocks at the surface of the earth. This break down of rocks is mainly caused by the geological processes that occur on the earth's surface. This process results in the formation of sediments that are transported and deposited in a new environment.
This weathering process primarily takes place in three different ways such as-
- Physical weathering- Here, the rocks are broken down by the physical agents such as wind, water, ice.
- Chemical weathering- Here the rocks are broken down when interacts with the chemical containing water.
- Biological weathering- here, the rocks are broken down due to the activities done by organisms such as plants and animals.
In the given condition, Quincy can see a real example of rock weathering in the high mountainous region, as in the mountainous region the rocks are frequently weathered and eroded by the agents such as wind, water, and ice.
Thus, the correct answer is option (D).
Answer:
Explanation:
The law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as the system's mass cannot change, so the quantity can neither be added nor be removed.
hope it helps
Explanation:
1.A physical property is an aspect of matter that can be seen or measured without changing its chemical composition. Examples of physical properties include color, molecular weight, and volume.
A chemical property is observed only by changing the chemical identity of a substance. In other words, the only way to detect a chemical is to perform a chemical reaction.
2.This property measures the ability of chemical change. Examples of chemical properties are reactivity, flammability, and oxidation state.
The physical properties of a substance do not involve any chemical reaction. These include density, color, mass, hardness, freezing points, electrical properties, and the like.
Chemical properties include the reaction of chemicals with other substances. These reactions lead to the disappearance of the raw material and the appearance of new materials that have different physical and chemical properties.
3.Chemical properties can be compared to physical properties; On the contrary, they are recognizable without changing the structure of matter. However, for many properties in the field of physical chemistry and other disciplines at the boundary between chemistry and physics, the distinction can be a matter for the researcher's point of view. The properties of materials, both physical and chemical, can be seen as metaphysical; This means that it is secondary to the principle of tangible reality. Multiple metamorphic layers are also possible.