Questions

Auto-immune disease :: Sometimes, due to genetic and other unknown reasons, the body attack self-cells. This results in damage to the body and is called auto-immune disease.

From the options,

-> Rheumatoid arthritis is an autoimmune disorder in which antibodies are produced against the synovial membrane and cartilage.

-> Vitiligo causes white patches on skin also characterised as autoimmune disorder.

-> Psoriasis is a skin disease that causes itchy or sore patches of thick red skin and is also autoimmune.

-> Alzheimer's disease is a chronic neurodegenerative disease. Alzheimer's disease is due to deficiency of neurotransmitter acetylcholine.

Hence, Alzheimer's is not the auto-immune disease.

The    HIV    virus    continuously    invades    and destroys  T-cells  (lymphocytes).  Eventually  the body can't replace the T-cells fast enough, and the  immune  system  deteriorates.  When  the immune  system has deteriorated to the point that it is unable to fight off diseases, a person is diagnosed with AIDS.

In astronomy, a syzygy is a straight-line configuration of three or more celestial bodies in a gravitational system.Solar and lunar eclipses occur at times of syzygy, as do transits and occultations.

Carbon dioxide (CO2) gas dissolved in water can cause water to become acidic.The acidity of water from dissolved CO2 can be reduced by a base such as baking soda (sodium bicarbonate).