Daily NEET MCQ- July 29, 2022 - NEET MCQ

Helium’s electronic configuration is 1s². As the last electron is filled in s-orbital, it belongs to s-block. Since the 1^st shell cannot accommodate any orbital than s, 1s² is completely filled orbital, hence making it, a noble gas. Noble gases are placed in p-block.

As per the outer shell configuration of hydrogen (that is 1s¹), it has only one electron in s-orbital making it eligible as an Alkali metal. It requires only 1 electron to obtain a noble gas configuration, which is a characteristic of halogen.

Non-metallic nature is defined as a tendency to gain electrons thus having high negative electron gain enthalpies, but the 18th group has no reactivity. So the non-metallic nature increases from left to right in groups leaving noble gases.

Addition of two vectors gives a vector as the result. The same goes for subtraction and cross multiplication. It is only when two vectors are operated through dot product, we get a scalar as the result.

Consider the graphical representation of these two vectors. When one vector is added to the other in the same direction, the lengths will be added. The resultant vector will bear the resultant length. Length is the magnitude of the vector. Hence the magnitudes add to give the magnitude of the resultant vector.

The formula for relative velocity is, Vector V_R = Vector V_A – Vector V_B. Finding relative velocity is an example of vector subtraction. In fact, finding the relative value for any vector quantity, we need to do vector subtraction.

In each body segment, except the first, last and clitellum, there are rows of S-shaped setae, embedded in the epidermal pits in the middle of each segment. Setae can be extended or retracted. Their principal role is in locomotion.

The body wall of the earthworm is covered externally by a thin non – cellular cuticle below which is the epidermis, two muscle layers – circular and longitudinal and an innermost coelomic epithelium.

The characteristic feature of the intestine of an earthworm is the presence of internal median fold of dorsal wall called typhlosole. Typhlosole helps in increasing the effective area of absorption for food and minerals. These structures are present after the 26^th segment except for the last 23^rd-25^th segments.

In earthworm, blood glands are present on the 4^th, 5^th and 6^th segments. They produce blood cells and haemoglobin which is directly dissolved in blood plasma as their blood does not have any respiratory pigment.