NEET Test 60

Triple Bond Strongest, 3 electron pairs shared, shortest bond 

Double Bond Middle, 2 electron pairs shared 

Single Bond Weakest, 1 electron pair shared, longest bond 

the bond types for each molecule or ion: 

CO, the lewis structure shows triple bond between the carbon and the oxygen (and -1 charge on the C and +1 charge on the O) 

CO₂ This lewis structure gives one double bond between each oxygen and the carbon. 

[CO₃]^2- double bond between one oxygen and the carbon, with single bonds between the other two oxygen atoms and the carbon. Because each of the oxygens want a double bond to

the carbon, they all fight over it (giving resonance structures), meaning that in the end, you get a bond something between a double and a single bond for each Carbon-Oxygen bond.

Therefore, this bond will be longer than a single bond, but shorter than a double bond.

We know that ΔG = ΔH – TΔS 

So, ΔG is positive at low temperature and negative at high temperature. 

Moreover, for a spontaneous process,  ΔG possess negative value and positive for a non spontaneous process.

This means ΔH and ΔS both must be positive.

hence, option 2 is correct.

Aspartame = 200 times sweeter than sugar

Saccharin = 300 times sweeter than sugar

Alitame = 2000 times sweeter than sugar

Sucralose = 400 – 800 times sweeter than sugar

Option (D) is right answer.

• Prophase I of meiosis I is further divided into five stages i.e., Leptotene, Zygotene, Pachytene, Diplotene, and Diakinesis.
• The following events occurring in meiosis I are as follows-

(a) Leptotene- condensation and coiling of chromatin fibers starts here. 

(b) Zygotene- pairing of homologous chromosomes take place which is known as synapsis. 

(c) Pachytene- exchange of genetic material between non-sister chromatids of homologous chromosome takes place which is termed as crossing over. 

(d) Diplotene- crossing over is completed and homologous chromosomes begins to separate from each other. 

(e) Diakinesis- Terminalisation of chiasmata takes place. Chiasmata is the point of attachment between the homologous chromosomes which is formed after dissolution of synaptonemal complex.

• Innate immunity is inborn immunity i.e., present at the time of birth.
• Innate immunity consists of 4 types of barriers which are- Physical barriers, Physiological barriers, Cellular barriers, and cytokine barriers.
• Cytokine barrier consists of interferons which are a type of protein secreted by virus-infected cells which protect non-infected cells from further viral infection.
• Interferons will act by inhibiting the viral replication as they stimulate synthesis of enzyme which inhibits the synthesis of proteins required for replication of the virus.
• So, they are used to control viral diseases, but they do not kill the virus.

• The accumulation of blood in veins of the legs over a long period of time may results in Varicose veins.
• This occurs mainly in the people who stand still all day as it causes the veins to stretch to point where the venous valves are no longer efficient.
• The leg muscles do not contract to compress the veins for upward blood movement.
• It results in the pooling of blood in the leg veins as blood is unable to ascend against gravity.
• To maintain the required supply of blood to the brain, heart does not receive enough blood, hence, person received less nutrients and oxygen due to this the person may faint and fall.

• Adrenal cortex secretes 20 steroids hormones which are known as cortical steroids or corticoids.
• These hormones are grouped into three major categories i.e., mineralocorticoids, glucocorticoids and sexcorticoids.
• Mineralocorticoids are steroid hormones which are released from the zona glomerulosa layer of the adrenal cortex.
• They maintain the electrolyte and water balance in the body e.g., aldosterone.
• Aldosterone causes the active uptake of Na⁺ ions from the nephric filtrate by acting over distal convoluted tubules and collecting tubules.
• Glucocorticoids are produced by zona fasciculata layer of adrenal Cortex.
• Gonadocorticoids are steroid hormones which are produced by zona recticularis.
• Example of sex corticoids are Androstenedione, Dehyroepiandrosterone and estrogens.