True or false $($ please correct the false $)1-$ The maximum efficiency of wind turbine is obtained when $\frac{V_{up}}{V_{\text{d}\text{o}\text{w}\text{n}}}=3.$

$2.$ As the temperature increases, the performance of PV cells decreases.

$3-$ In the wind turbine, the lower pressure air pocket is formed in the wind upstream side.

$4-$ The minimum spacing between the wind mills is $2R.$ VC

$5-$ The photovoltaic cell produces $AC$ current.

$6.$ The absorber part in the solar heater is made of bright copper. $x$

$7-$ The solar chiller uses the water as refrigerant and $\frac{\text{A}\text{m}\text{m}\text{o}\text{n}\text{i}\text{a}}{H_{2}a}$ absorbent$.x$

$8.$ The box cooker is the least efficient solar cooker.

$9.$ The Albedo is about $25\%$ of the total solar radiation. $x$

$10-$ The Nuclear power is considered renewable source of energy.