Write the name of the metal nanoparticle used to remove E. coli bacteria from water.
When hydrogen peroxide is added to an acidified solution of KI, iodine (I2) is liberated. In this case, hydrogen peroxide acts as?
Explain the construction of a spherical wavefront by using Huygens' principle.
The slope of the tangent to the curve \( x = \sin\theta \) and \( y = \cos 2\theta \) at \( \theta = \frac{\pi}{6} \) is ___________.