An exoplanet is a planet that orbits a star outside of our solar system. These planets are found in other star systems and are not part of the Sun's family of planets. Exoplanets can vary in size, composition, and distance from their host star, and their discovery has expanded our understanding of the diversity of planetary systems in the universe. Scientists use a variety of methods, such as the transit method and the radial velocity method, to detect and study exoplanets. **

While it is fun to imagine an exoplanet made of chocolate, it is highly unlikely to exist in reality. Exoplanets are typically composed of rock, gas, or ice, and the conditions required for the formation of a chocolate planet are not found in the universe. Chocolate is a product of organic matter and requires specific conditions such as the presence of cocoa trees, sugar, and other ingredients that are not found in the vast majority of exoplanets. Therefore, while it is a fun idea, a chocolate exoplanet is not scientifically feasible. **

As of now, images of Proxima Centauri b have not been taken directly. Due to the vast distance between Earth and the exoplanet, it is extremely challenging to capture images of it using current technology. Most of the information we have about Proxima Centauri b comes from indirect methods such as studying its parent star's light or analyzing data from telescopes. **

The nearest exoplanet outside of the solar system is Proxima Centauri b, which orbits the red dwarf star Proxima Centauri, the closest star to the Sun. Proxima Centauri b is located approximately 4.24 light-years away from Earth and is considered to be within the habitable zone of its star, making it a prime candidate for the search for extraterrestrial life. This exoplanet was discovered in 2016 and has since been the subject of extensive study and observation. **

It is difficult to predict when we will find the first exoplanet with intelligent life, as it depends on various factors such as the advancement of technology, the discovery of suitable exoplanets, and the ability to detect signs of intelligent life. While the search for extraterrestrial intelligence is ongoing, it is uncertain when we will make such a groundbreaking discovery. However, with the continuous advancements in space exploration and technology, it is possible that we may find evidence of intelligent life on an exoplanet in the coming decades. **

Renewable resources and sustainable resources are related concepts but not exactly the same. Renewable resources are those that can be replenished naturally over time, such as sunlight, wind, and water. Sustainable resources, on the other hand, refer to resources that are managed in a way that meets current needs without compromising the ability of future generations to meet their own needs. While renewable resources are often considered sustainable, not all sustainable resources are necessarily renewable, as some non-renewable resources can be managed in a way that ensures their long-term availability. **

Smart home systems have the potential to be sustainable, as they can help reduce energy consumption and waste. For example, smart thermostats can optimize heating and cooling, reducing energy usage. Additionally, smart lighting systems can be programmed to turn off when not in use, saving electricity. However, the production and disposal of smart home devices can contribute to electronic waste, so it's important to consider the lifecycle impact of these systems. Overall, with proper use and disposal, smart home systems can contribute to sustainability efforts. **

No, the radius of exoplanet Kepler 90h is not provided in Material 4. The material only mentions that the exoplanet is located in the Kepler-90 system and is one of eight planets orbiting the star Kepler-90. The specific radius of Kepler 90h is not given in the provided information. **